It should not be too surprising that meteorites are not just rocks that have fallen from space to a final resting place on the surface of the Earth. Meteoroids fall on bodies throughout our solar system. Opportunity, the rover currently at work on Mars, recently came across a metallic-looking rock lying in the desert sands of Meridiani Planum. Steve Squires, primary science investigator for the Mars Exploration Rover (MER) mission, recently confirmed to various publications that the rock is a meteorite. It has an iron-nickel composition.
Although not a native martian object, the meteorite could reveal something about the martian atmosphere at the time it fell to Mars. Opportunity will spend some time with the meteorite to gather further data.