Life in the Universe

Life in Our Solar System

What was the evidence for fossilized life in the Martian meteorite ALH84001?

Dozens of scientific research groups are studying this Martian meteorite—and pieces of it—to figure out if there indeed is fossilized life embedded within it. The primary evidence consists of tiny, sausage-shaped markings in the meteorite less than a billionth of an inch long. These imprints resemble some kinds of fossilized bacteria found in rocks on Earth. Some of them are assembled in long chains of iron-rich magnetite crystals, which on Earth are usually produced by biological processes in microorganisms.


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