Martian meteorites are chunks of rock churned up from the planet Mars, usually as a result of an asteroid impact, and expelled from its gravitational sphere of influence. As you can imagine, they’re pretty rare on Earth; in fact, only 61 of the 41,000 meteorites that have ever been discovered on this planet have been definitively identified as having Martian origins.
The most recent confirmed meteorite from Mars to hit Earth has been named Tissint and it’s also the largest to date, weighing 1.1 kilograms (2.5 pounds). It was found in the desert in southern Morocco last year and was classified as shergottite, a rock that came from somewhere within Mars’s molten magma layer after an impact or expulsion by a volcano.
These meteorites are highly prized by scientists, who don’t have any other practical way of analysing Martian rock samples. More importantly, Tissint can also provide clues as to the possibility of life on Mars; because it landed in a relatively lifeless area of Earth and was recovered quickly, any microfossils and Martian minerals altered by the presence of water will be relatively uncontaminated.