The two Mars rovers currently exploring the red planet have found a scientific treasure trove of strange looking rocks and dunes, as well as more evidence that Mars once contained water, NASA announced yesterday.
The Mars rover named Spirit recently roamed an area called the Columbia Hills, which reach about 30 feet above a flat plain. In this area, Spirit researched the rocks there and it was found they had higher concentrations of Sulfur and chlorine.
Steve Squyres, the principal investigator for the instruments aboard the Spirit and the Oppurtunity said: "Here, we have a more thorough, deeper alteration, suggesting much more water." Source