Download The Mechanism and History of Life

The Mechanism and History of Life
Hannah Cebulla, Nikoli Brown, Katherine Lee, Nate Johnson,
Jeremiah Hashley, Brett Gordon
Earth’s Early Chemical Composition
Pre-Earth
-Protoplanetary disk
-Roughly the mass of Jupiter
-Heavier elements are closer to the Sun
-Silicate dust and ice
-H2, He are the dominant gases
-99% gas
Williams, Jonathan P., and Lucas A. Cieza. "Protoplanetary Disks and Their Evolution." Annual Review of Astronomy and Astrophysics (2011):
67-117. University of Hawaii Institute of Astronomy. Web. 11 Nov. 2016.
4.6 billion years ago
-Core accretion model
-Differentiation
-Moon formed
-Dominant elements: Fe (320,400 ppm),
O (316,700 ppm), Mg (148,600 ppm), Si
(145, 900 ppm), and Ni (17,200 ppm)
-Most oxygen bound up as oxides rather
than as O2
Kargel, J. S., and J. S. Lewis. The Composition and Early Evolution of Earth. N.p.: Icarus, Sept. 1993. PDF.
4 billion years ago
-The Late Heavy Bombardment ends
-Oceans form
-Atmosphere forms
-Most prominent chemicals are H2O (2699 ppm), C (526 ppm), and N (1.68 ppm)
-Atmosphere comprised mostly of H2, H2O, NH3, CH4, and H2S
Marty, Bernard. "The Origins and Concentrations of Water, Carbon, Nitrogen and Noble Gases on Earth." Earth and Planetary Science Letters
313-314 (2012): 56-66. ScienceDirect. Web. 11 Nov. 2016.
3.5 to 4 billion years ago
-Organic molecules originate
-Miller-Urey experiment
-differing origin theories
-Most important molecules for life: C, H2O, N, O, PO3
Sagan, Carl. Cosmos. New York: Random House, 1980. Print.
3.6 billion years ago
-Life starts
-Organic carbon discovered in ancient
lava
-May have begun around deep-sea
hydrothermal vents
-Simple, single-celled organisms
-Doesn’t use O2
Furnes, Harald, Neil R. Banerjee, Karlis Muehlenbachs, Hubert Staudigel, and Maarten De Wit. "Early Life Recorded in Archean Pillow Lavas."
Science 304.5670 (2004): 578-81. Science. Web. 12 Nov. 2016
3.4 billion years ago
-Photosynthesis...ish
-Not photosynthesis in its modern sense
-Convert energy from the sun into
energy for the cell
-Still no oxygen
-Probably didn’t use water
Blankenship, Robert E. "Early Evolution of Photosynthesis." Plant Physiology 154 (2010): 434-38. Web. 12 Nov. 2016.
3 billion years ago
-Plate tectonics puts N2 into
atmosphere
-Nitrogen is very important for life
-Evidence: transition from mafic to
felsic rocks
Tang, Ming, Kang Chen, and Roberta L. Rudnick. "Archean Upper Crust Transition from Mafic to Felsic Marks the Onset of Plate Tectonics."
Science
351.6271 (2016): 372-75. Web. 13 Nov. 2016.
2.4 billion years ago
-Great Oxidation
-Cyanobacteria: first real photosynthesis
-Drastically changes the composition of the atmosphere: less CH4, far more O2
-First mass extinction
-Leads to the first snowball Earth (~2.2 billion years ago)
Sessions, Alex L., David M. Doughty, Paula V. Welander, Roger E. Summons, and Dianne K. Newman. "The Continuing Puzzle of the Great
Oxidation Event." Current Biology 19.14 (2009): R567-574. ScienceDirect. Web. 13 Nov. 2016.
The Definition of Life on Earth
Criteria of Life
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Homeostasis (resistance to change)
Metabolism (taking in energy)
Organization (one or more cells)
Reproduction
Response to stimuli
Growth (increase in size, not just accumulation)
Adaptation (needed in process of evolution)
Exceptions to Definition The large gray area in the definition of life:
Viruses
When in contact with host:
■ Active
■ Can reproduce when host
is “infected”
■ Reacts to environment
■ Behaves like a living
organism
Without contact with host:
■ Dormant, inactive
■ Cannot reproduce or
replicate itself
■ Static organic particle (these
are known as Virions)
■ No internal biological
activities
Crystals
Exhibit many of the characteristics of living things:
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Growth
Take in energy by chemicals
Response to stimuli
“Adapt” to environment
But it doesn’t have a nervous system and can’t reproduce
Its growth is accumulative, not increase in different parts of organism
Why life on Earth is unique
Life depends on the characteristics of Earth
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Orbits the sun (a star of a certain size)
Orbits at a certain distance (and is almost circular in orbit)
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This determines the temperature (along with the atmosphere on Earth)
Covered in liquid water (needed for life)
Within the considered “habitable zone” around the sun
Temperature is within a certain range for living
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Spin of Earth contributes to constant temperature
Life outside of earth (what we look for)
We look for another earth
Same characteristics of earth that
could support human life.
Water and atmospheres
Habitable zones around a star (one
similiar to the sun)
But what if life outside of Earth
looked completely different?
Kepler-186f
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(one of five planets in system)
Similar size to Earth
Within habitable zone of
Kepler-186 System
Composition is most likely to
be rocky
490 light years away
Orbit of about 130 days
around red dwarf star
We are looking for earth-like planets
which means earth-like life.
Microbiologist “Venkat”
Experimenting with life in space (fungi and bacteria) and how space affects life
Samples sent on SpaceX Dragon Capsule with two microbial tests
Microgravity effects on tiny organisms
Detected radiation-resistance bacteria
Work shows
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Effects on astronauts in space (health)
New compounds for radiation therapy and cancer treatments
what kinds of life can survive in space and on planets with different compositions
and atmospheres
Abiogenisis
Inorganic Matter
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Living Things
What Does Life Need?
Energy
Water
Safe Environment
Variety of Chemicals
Energy
Activation Energy
Gibbs Free Energy Equation
Ex. Micelle
∆G=∆H-T∆S
Liquid Water
Great Solvent
-Acts as Acid and Base
-Holds ions
Ex. Miller-Urey Experiment
Safe Environment
Protection from radiation
Protection from collisions
Ex. Life by land and by sea
Important Chemicals
Meteorites
Rocks and Minerals
Iron
How to Find the Origins of Life
Bottom Up or Top Down Approach
- Place chemicals and conditions to create life (Miller-Urey)
- Look at life and work backwards (Craig Venter)
Metabolism
Breaking and building molecular bonds
Using energy of one reaction to power another reaction
Ex. Iron and Clay provide surfaces for the reactions to take place
Replication: Finding LUCA
355 genes common to all life on earth
Genes produce a CO2 and N2 fixing with H2 dependant and thermophilic.
Metabolism Vs. Replication
Modern Chicken and Egg
Most people believe that metabolism was first
Provides and environment for replication to occur
Ex. http://biochemical-pathways.com/#/map/1
So What Happened? What Do We Know?
Earth forms from basic chemical compounds
Earth cools, allowing for deep vent formation T=100-150C
Basic Elements form chemical monomers ex. Amino Acids etc.
Chemicals attach to surface creating specific environments
These environments localize metabolic processes
Metabolic process provide environment for RNA replication
All processes contained in cell wall
The Theory of Evolution
What is it? A quick summary
The theory of evolution by natural selection is the process in which organisms change
over time as a result of changes in heritable physical, or behavioral traits.
All organisms are thought to have a common ancestor as well!
“It is not the strongest of the species that survive, nor the most intelligent, but the one
more responsive to change.” - Charles Darwin… Who is he?
Charles Darwin (1809-1882)
Went to the galapagos, and saw something strange…
Various species of finches that varied from island to island
WHY!?
Wrote his book The Origin of Species when a majority of the world believed in some
form of “Creator”.
Natural selection and adaptations.
Natural selection is essentially an organism's ability to survive in various conditions,
and to successfully reproduce.
Adaptations are when an organism changes to be better suited to its environment
usually driven by mutations.
The craziest example of this, are whales!
Let’s draw an example
Evolution Telephone
So for those of you that couldn't follow my drawing, we have a classroom activity to try
out.
End
Evolution today.
Peppered moth story
The History of Life’s Evolution
Brett
By the end of my section you should be able to
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Understand the basic timeline of life on Earth
Understand the basic timeline of the geology of Earth
Know why extinctions were important for biodiversity
Evaluate what your favorite looking animal was of all of history.
Be able to find one TRULY cool fact per slide
Major Events overview
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Life Started (3.7 BYA)
Photosynthesis (3..7-3.4 BYA)
Plate tectonics (3 BYA)
Oxygen Atmosphere (2.4-1.6) BYA)
Multicellular Life (2 BYA)
Endosymbiosis (2-1 BYA)
First Sex (1.2 BYA)
Shell animals (535 MYA)
Plants on Land (465 MYA)
Mass Extinction #1 (460 MYA)
Sea to land animals (375 MYA)
Devonian Extinction (375 MYA)
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Reptiles (320 MYA)
Pangea (300 MYA)
Permian Extinction(252 MYA)
Mammals (220 MYA)
Triassic Extinction (201 MYA)
Feathered Birds (160 MYA)
Flowers and Grains (130 MYA)
Death of Dinosaurs (65 MYA)
C4 Photosynthesis (32 MYA)
First Hominins (13 MYA)
Life starts (3.5 Billion Years)
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3.5 billion years old
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Confirmed by fossils
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Stromatolites (microorganism mats)
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Energy from sun
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In the water
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Rocks and matter found in crust
NO plate tectonics at this point.
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How old is this?
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3.5 BYA-.201 BYA
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=3.29 billion years before ‘Titanic
Dinosaurs
Stack of 1 billion dollars
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67.9 miles
Photosynthesis-ish (3.7-3.4 BYA)
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No modern photosynthesis
Just used the sun to reduce (gain electrons)
and store energy in bonds
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Could have been iron, or anything to
conduct redox reaction
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Thought to be hydrogen and sulfur, NOT
water
1937, Robert Hill discovered plants can
4 Fe3++2H2O → 4Fe2+ + O2 + 4H+
How do we know?
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There was life, but there was no O2
deposition clues.
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Deep sea vents hold bacteria that live off of
sulphur and hydrogen reduction
Plate Tectonics!! (3 BYA)
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Puts nitrogen into the atmosphere!
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Evidence?
Recycling of rocks
Not totally for certain on time.
Soaks up CO2
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Coolest one: Paleomagnetism
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Why is Nitrogen important?
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DNA
RNA
Proteins and peptide bonds
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Magnetite in lava rocks point north when
cooled.
All basalt doesn’t point in the same direction!
Poles are assumed to stay at axis
The Great Oxidation Event (2.4 BYA)
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Bacteria began to photosynthesize!
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Again? (Oceans were full!)
CO2 and H2O this time
Made “Snowball Earth”
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Just enough crust showing to continue life
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Caused by O2 stripping Methane from
atmosphere
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How do we know?
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Iron Oxide precipitation in oceans
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Means oxygen saturated water, and began
staying in atmosphere
Endosymbiosis (2-1 BYA)
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What is it?
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Cells eat other cells!
Like eating a chef and they are always being
there to cook!
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What is the evidence?
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Mitochondrial DNA is more closely related
to bacteria than parent cell!
Not readily accepted until 1960’s!
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Why is this important?
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Allows ‘us’ to make ATP
Allows plants to make sugars
Helped life become complicated!
Multicellular Life (2.1 BYA)
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Cells of same code become organized
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Evidence
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Why is this important?
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Bigger container
More organization
Allows resilience!
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Shale found in Gabon of ‘centimeter-sized
structures interpreted as organized and spatially
discrete populations of colonial organisms living in
an oxygenated marine ecosystem.
Extremely rare in the fact that all other rocks of this
age “ have experienced thermal overprinting from
burial diagenesis and metamorphism, [these
samples] have not.”
Last evidence was 575 million years ago
First Sex (565 MYA)
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It was very special? Nah...
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They didn’t catch feelings
Why is it important?
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Sponge like creatures in ancient oceans.
Creates increased rate of evolution
Genetic variety for multicellular
Red Queen hypothesis
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“I don’t wanna shmang, you and your
whole family sick all the time”
My theory: Mutation in DNA synthesis and
the rest might work?
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Evidence?
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F. dorothea in 2005 (see left) in Australia
(back at it again with Earth’s History)
Ordovician Extinction (444 MYA)
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What caused the extinction?
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Ice age from CO2 being sucked by new rocks
(remember tectonics!?!)
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What was there: Sea Creatures
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Graptolites
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Filter feeders
Trilobites
Conodonts
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Toothy invertebrates
Left room for FISH!
The Great Dying aka Permian Extinction (252 MYA)
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What caused it?
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Volcanos created Greenhouse effect
Methane released by microbes in response
Oceans acidified
What was there?
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Marine invertebrates
Ferns
Synapsids (mammal-like reptiles)
96% of ocean life died
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300 million years wasted
50% land life died
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Who filled the gap?
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Dinosaurs!
Seed plants!
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conifers
Triassic Extinction (200 MYA)
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What caused it?
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Debated
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Pangea rifting led to warming
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Methane release from mild warming
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Asteroid
Who was there?
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Dinosaurs
Marine reptiles
brachiopods
Who filled the gap?
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More dinosaurs! (Jurassic Park)
Cretaceous Extinction (65 MYA)
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What caused it?
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Most likely Asteroids
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Made earth real dark
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No more photos please!
Could also be more plate tect
Who went extinct?
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Dinosaurs
Marine invertebrates
Crocodiles
Ancestors of modern birds
Who filled the Gap?
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LIttle mammals
Plants of today!
Alternative Life Forms
Extremophiles
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Defined as organisms that thrive under extreme conditions
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Microbes thrive in conditions that would terminate humans in seconds
The term is generally used to describe prokaryotes but can also be used to
describe bacteria and archaea
Most extremophiles are microbes
Anaerobic Organisms
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An organism that does not require
oxygen for growth
In some cases, oxygen is actually
toxic to the organism
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Obligate anaerobes
Anaerobic organisms do not produce
energy from carbon dioxide, rather,
they metabolize inorganic
compounds
Prokaryotes
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Do not require free oxygen to
sustain themselves
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Not harmed by free oxygen in
their environment
Single celled organisms
Lacking membrane bound
organelles
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Some have chloroplasts and can
respire via photosynthesis
Cyanobacteria
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Single celled
Survive through photosynthesis
Generate about 16x more energy than
anaerobic organisms
Capable of surviving in extremely
harsh conditions
The Oxygenation Event
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Responsible for the evolution of aerobic
respiration and the catalyst for the
evolution of stable and successful life on
Earth
Proves that the study of extremophiles
is important in the search for
extraterrestrial life
Snowball
Snowball Earth
Earth
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In a relatively short time
period:
○ Oxygen levels
skyrocketed, causing the
oceans to be inhabitable
to some anaerobic
organisms
○ The methane and CO2
rich atmosphere was
dominated by oxygen,
causing temperatures to
drop due to a lack of
greenhouse gasses
○ Many scientists theorize
that the severity of this
event is what caused
cellular differentiation
Antarctica
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Excellent representation of earth
during its snowball and ice age
periods
Organisms that survive here are not
necessarily anaerobic, but can survive
extremely low temperatures and a
relatively high pH balance
Colwellia is a type of deep sea
anaerobic bacteria that is found in ice
samples from Antarctica
○ Similar environments and
organisms may be found on
other planets
Yellowstone
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Thermophiles
○ Metabolic processes
■ Photosynthesis
● Occurs in plants, algae, and
cyanobacteria
■ Fermentation
● Extremely inefficient compared
to aerobic cellular respiration
● Oxygen is the most efficient
electron acceptor of the ETC
due to its high electronegativity
○ Process of cellular
respiration is called
oxidative phosphorylation
and is about 16 times
more efficient than
fermentation
Hydrothermal Vents
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Form at locations where
seawater meets magma
Extremely harsh
environment
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Ejected fluids are full of
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elements such as iron,
calcium, and silicon
Water reaches up to 700℉
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Home to numerous
extremophiles