Dr. McMahon and co-authors determined that sedimentary rocks made of compacted mud or clay are the most likely to contain fossils.
These Martian rocks are rich in iron and a mineral called silica, which helps preserve fossils.
These rocks formed during the Noachian and Hesperian periods (3-4 billion years ago).
At that time, the planet’s surface was abundant in water, which could have supported life.
“The rocks are much better preserved than those of the same age on Earth,” Dr. McMahon and co-authors said.
“This is because Mars is not subject to plate tectonics — the movement of huge rocky slabs that form the crust of some planets — which over time can destroy rocks and fossils inside them.”
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