Mars, raw feed, Sol 100, from the ChemCam.
I am only an amateur biologist and an amateur geologist. What I've done the most of is hiking through Big Bend National Park, and what I see in these Mars photos resembles the desert. Without, of course, the spiky and painful flora that festoon the landscape.
It may seem irresponsible to start guessing what they've found, and what they're so excited about. But we're going to do it anyway. Follow me below the biological crust.
Here's a shot of Mars.
Mars, Sol 107, raw feed from the right nav camera
Here's a shot of a biological soil crust in the desert.
Biological soil crust
Here's the shot that I posted in the intro. It's a closeup shot of the surface of Mars. You'll note the lumpy crust that covers the surface - it doesn't go down below the mark of the rover scoop.
Mars, raw feed, Sol 100, from the ChemCam.
Biological soil crusts are "the community of organisms living at the surface of desert soils. Major components are cyanobacteria, green algae, microfungi, mosses, liverworts and lichens." The interesting thing about these soils is that they're different for different environments. Some are larger and darker in color, and some are smaller because of cooler climates and low moisture.
A closeup of a biological soil crust.
So what's next? I'm sure NASA is scrambling to figure out that very thing. We need a closer examination of soil crusts in environments that closely mimic the Mars landscape. We will not be able to find the low-oxygen environment we need. This will have to be replicated in the laboratory, under carefully controlled conditions. The good part is that we have a good idea of what Mars is made of. And you know that NASA won't say a word until they're absolutely certain what they're looking at.