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.

The rock, which scientists have dubbed "Pinnacle Island," appeared in front of Opportunity for one of two reasons, NASA says: the rover flipped the rock as it maneuvered, or the rock landed there after a nearby meteorite impact. Either way, the intrepid Opportunity now has something new to look at. "[The rock] obligingly turned upside down, so we're seeing a side that hasn't seen the Martian atmosphere in billions of years and there it is for us to investigate," Squyres said. "It's just a stroke of luck."