The Martian meteorite that caused a minor sensation in 1996 when possible signs of Martian life were detected may indeed hold evidence of life afterall. Scientists have been analyzing the magnetite crystals in the meteorite and determined that 25% of those crystals meet the most strict criteria for biologically-produced magnetite. This evidence strengthens the contention that life once existed on Mars.
While these are just little bacteria, finding life on another planet is a major disovery. If planets like Mars could once have harbored even simple lifeforms at one point that means that the possibility of finding life on other worlds that much greater.