After a rock from Mars was discovered in the Sahara desert, scientists investigated it for a year—and they're fascinated by what they've learned. At an estimated two billion years old, the rock is older than most Martian meteorites and holds more water, the AP reports. And it offers an opportunity for scientists to study the planet without having to drop by. "Here we have a piece of Mars that I can hold in my hands," says an expert at the University of New Mexico.
So how did the rock get here? Experts think a giant object, such as an asteroid, hit Mars and knocked rocks into space. Some 65 have now been found on Earth, typically in the Sahara or Antarctica, and this one, dubbed "Black Beauty," is the second-oldest known Martian meteorite that formed from a volcanic eruption. Scientists know it's from Mars thanks to chemical analysis. The rock's high water content points to interaction with water when the planet was mostly dry. Future tests will establish how long the rock floated in space and how long it had been sitting in the Sahara. (Read more Mars stories.)