A meteorite found in the Sahara, one of the oldest ever to come from Mars, offers evidence that life could have existed there more than two billion years ago, researchers say.

The 0.7-pound fragment contains more water than any other known Martian meteorite. “It’s about 6,000 parts per million of water,” said Carl B. Agee, a planetary scientist at the University of New Mexico who led the study. “That’s the water locked into the mineral structure of the meteorite.”

By comparison, there are more than 100 other known meteorites from Mars, and most have a water content of 200 parts per million.