NASA press release today, regarding the Martian meteorite Yamato 000593 (Y000593):
"The team reports that newly discovered different structures and compositional features within the larger Yamato meteorite suggest biological processes might have been at work on Mars hundreds of millions of years ago."
"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."