David DelMonte writes "Space.com is reporting on the discovery of seven dark spots near the Equator on Mars. The thinking is that these are cave openings. The openings are the size of football fields, and one of them is thought to extend approximately 400 feet below the surface.'The researchers hope the discovery will lead to more focused spelunking on Mars. "Caves on Mars could become habitats for future explorers or could be the only structures that preserve evidence of past or present microbial life ," said Glenn Cushing of Northern Arizona University, who first spotted the black areas in the photographs.'"