This is a microphotograph of a meteorite from Mars, and is one of the pieces of evidence proposed to show that there was once life on Mars. The vaguely worm-shaped object in the center of the picture is somewhat similar in shape to bacteria on the Earth; however, it is considerably smaller than any confirmed bacteria on the Earth, and is in fact smaller than many biologists believe life can ever be.
To add fuel to the fire, there are some biologists who claim to have found bacteria of this size on Earth, but the issue is still hotly debated.
While the group that claims to have found evidence of life in the meteorite have a number of other pieces of evidence, each is similarly being questioned. Whether or not this meteorite contains evidence of life is still very much an unanswered question.
PtyS 195 (Colloquium 4), being offered this semester, is all about the exploration of Mars.
Colloquium 2 of PtyS 195 deals with life on Mars, in both fact and fiction.
PtyS 106 is the regularly-offered course that talks the most about Mars.
PtyS 403, PtyS 407, and PtyS 411 also partly deal with Mars.
PtyS 105 deals partially with the development of life on Earth.
PtyS 107 deals with the Earth, including life on Earth.
Some other places you can find information on Mars include: