We all remember the famous Allan Hills meteorite (Allan Hills 84001) that – in 1996 – was thought to have evidence of fossil bacteria on it.
By the way, how do we know that these rocks were from Mars?
The SNC meteorites are from Mars
NASA Rover Confirms Mars Origin of Some Meteorites
Anyway, recently Astrobiology Journal reported that meteorite Yamato 000593, found in Antarctica in 2000, “contains microscopic burrows and spheres that resemble the marks microorganisms leave when they eat through rocks on Earth”.
From the folks at NASA:
“The team found two distinctive sets of features associated with Martian-derived clay. They found tunnel and micro-tunnel structures that thread their way throughout Yamato 000593. The observed micro-tunnels display curved, undulating shapes consistent with bio-alteration textures observed in terrestrial basaltic glasses, previously reported by researchers who study interactions of bacteria with basaltic materials on Earth.
“The second set of features consists of nanometer- to-micrometer-sized spherules that are sandwiched between layers within the rock and are distinct from carbonate and the underlying silicate layer. Similar spherical features have been previously seen in the Martian meteorite Nakhla that fell in 1911 in Egypt. Composition measurements of the Y000593 spherules show that they are significantly enriched in carbon compared to the nearby surrounding iddingsite layers.”
Paired with the recent discoveries suggesting that Mars once had abundant water, this is opening the way to the possibility of life in space, in a form that even the most cautious scientist can begin to accept.