Mystery rock suddenly appears near Mars rover, puzzling scientists

A "jelly doughnut-sized" rock has appeared in front of the Opportunity rover on Mars, and scientists can't figure out where it came from, Discovery News reports. The discovery was revealed by Mars Exploration Rover lead scientist Steve Squyres in a "10 years of roving Mars" keynote at NASA's Jet Propulsion Laboratory last night. "Mars keeps throwing new stuff at us!" he exclaimed, discussing past rover findings, but this time, he meant it literally.