The Allan Hills 84001 Meteorite which landed on earth has been examined and they’ve discovered that the tiny magnetite crystals it contains are chemically consistent with being formed in bacteria – they’re basically little fossils. They’re pretty sure the rock, which has floated around for around 16 million years, comes from Mars as it matches chemical compositions with the relative proportions of various gases measured in observations of the atmosphere of Mars made by the Viking spacecraft in the 1970s.

Evidence of life on Mars lurks beneath surface of meteorite, Nasa experts claim – Times Online.