This image from the microscopic imager instrument on NASA's Mars Exploration Rover Spirit shows a feature called "String of Pearls" that resides within the area dubbed "Hanks Hollow." The "string" consists of a set of bright spots. These are the partially exposed interiors of rocks that were broken-up when Spirit's wheels roved across this surface. Scientists believe the rocks exposed in Hank's Hollow may have been generated or modified by water-rich fluids. The image was taken on sol 177 (July 2, 2004).