a coal-coloured rock from Mars that landed in the Sahara desert.
A year-long analysis revealed it is quite different from other Martian meteorites: not only is it older than most, it also contains more water.
The baseball-size meteorite, estimated to be 2bn years old, is strikingly similar to the volcanic rocks examined by the Nasa rovers Spirit and Opportunity on the Martian surface.
Carl Agee, director of the Institute of Meteoritics and curator at the University of New Mexico who led the study
About 65 Martian rocks have been recovered on Earth, mostly in Antarctica or the Sahara. The oldest dates back 4.5bn years to a time when Mars was warmer and wetter. About half a dozen Martian meteorites are 1.3bn years old and the rest are 600m years or younger.
