A class of seventh-graders in Cottonwood, California, who were participating in a special NASA program, spotted an unusual hole on the surface of Mars.

Scientists now think the hole is a pit crater that leads into a buried Martian cave. It's estimated to be 620 feet wide and at least 380 feet deep. Scientists are excited because unknown minerals could be hidden in these caves. One theory suggests ancient volcanoes created the tunnels. The tunnels then became hollowed out once the Martian lava cooled. Holes found are like skylights into these unexplored caves.