I’m no paleontologist but I’ve long found stromatolites to be really interesting. They’re one of the earliest known forms of complex life on Earth. These layered mounds created over hundreds and thousands of years by cyanobacteria—basically “microbial reefs”— have existed on Earth for over 3.5 billion years. Today they can be found in active, living form in just a few marine locations like Shark Bay, Australia and Storr’s Lake in the Bahamas (and recently also found living on land in Tasmania!) but they are widespread in Earth’s fossils—like the ones photographed above in Nevada during NASA field exercises—and perhaps they’re something we might find in similar form on Mars as well.
Description from the NASA image archive:
Made from fossilized microbes and sediment, these rounded rocks are stromatolites that were found in a dry lakebed during the field exercise. Scientists hope to find something similar in the dry lakebed Perseverance will be exploring on Mars.
I’ve never seen stromatolites in fossil or living form myself, but until today I didn’t know they could be found just sitting out on the rocks like that! I’ve always in my mind associated them with the western coast of Australia. It would be amazing for the next Mars rover to find something similar on Mars now… very likely not still alive, but a sure sign that the planet was once a habitable—and even inhabited—place during its history.