These mats tend to build up in layers, and often form structures known as stromatolites. You can find some examples both at the NASA team's site (http://nai.arc.nasa.gov/students/this_month/page2.cfm) and here: http://www.evolutionaryresearch.org/stromatolites.htm
There used to be a page up, claiming to show the remains of actual stromatolites on Mars, but it seems to be completely gone now (Spirit Finds Stromatolites, http://www.xenotechresearch.com/marsstro.htm). The Wayback Machine has it at http://web.archive.org/web/20081120022703/http://www.xenotec... but I'd probably rank its credibility with the Face On Mars.
EDIT: Just to make it clear, all actual stromatolites in these links are definitely of terrestrial origin! (At least, I think they are)
These mats tend to build up in layers, and often form structures known as stromatolites. You can find some examples both at the NASA team's site (http://nai.arc.nasa.gov/students/this_month/page2.cfm) and here: http://www.evolutionaryresearch.org/stromatolites.htm
There used to be a page up, claiming to show the remains of actual stromatolites on Mars, but it seems to be completely gone now (Spirit Finds Stromatolites, http://www.xenotechresearch.com/marsstro.htm). The Wayback Machine has it at http://web.archive.org/web/20081120022703/http://www.xenotec... but I'd probably rank its credibility with the Face On Mars.
EDIT: Just to make it clear, all actual stromatolites in these links are definitely of terrestrial origin! (At least, I think they are)