From a distance scientists at first thought Marquette Island was another meteorite. Now, they think it was hurled up from deep beneath Mars' surface by an ancient impact. Since it may be harboring Martian secrets of the planet's environment at Meridiani Planum a long, long time ago, Opportunity took a break from its long journey to Endeavour crater and spent two months checking it out.

NASA / JPL-Caltech / Cornell / enhancement by Stuart Atkinson