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. More at Mail Online.