DISCOVER
A cluster of 3.4 billion-year-old fossilized cells.
Geologists have found fossils of microorganisms from 3.4 billion years ago, which may be the oldest fossils ever uncovered. Since these microbes date from a time when Earth’s atmosphere was still oxygen-free, astrobiologists could look for similarly structured microbes when searching for extraterrestrial life.
How the Heck:
These microfossils, as such single-celled fossils are called, were found in a sandstone deposit in Western Australia—an area that was likely a beach on one of Earth’s earliest islands—nestled between ancient grains of quartz sand.
The researchers dated the rock formation to 3.4 billion years old. Back then, the atmosphere was thick with methane, not oxygen, and Earth’s oceans were far warmer than they are today, likely about 110?F.
With microfossils so tiny and so old, the big challenge for scientists is proving that what they’ve found really are fossils, rather than non-biological aberrations or patterns in the rock. Using a variety of methods, the research team gathered several types of evidence suggesting—albeit circumstantially—that they’ve found bacterial fossils.
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