NASA scientists are baffled by a piece of rock that has mysteriously appeared in front of the Mars Opportunity rover. The doughnut-sized rock, nicknamed Pinnacle Island, showed up in photos taken a few days ago but is noticeably absent from photos snapped earlier this month. The six-wheeled rover has not moved in several weeks due to rough weather conditions on the Red Planet. News of the strange rock was announced by NASA Mars Exploration Rover lead scientist, Steve Squyres.

What explains the rock’s sudden appearance? Squyres offered a couple of possible explanations: the rover might have flicked the object while navigating the tricky terrain, or the rock might have landed on the Martian surface after a nearby meteor impact.

The researchers say the first explanation is more likely. They plan to study the rock further to determine where it came from.

Who knows? Maybe the Mars Rat flicked it there!