NASA’s Spirit rover found a new class of rock on Mars that provides additional clues to the planet’s watery past. The rock, named “Peace,” is an exposure of bedrock in the Columbia Hills within the Gusev Crater, where Spirit landed 13 months ago. Though appearing mundane in a black-and-white image, the rock is significant to scientists for what they’ve learned by digging into it and analyzing it with a suite of instruments. Peace contains more sulfate salt than any other rock Spirit has examined.