- Mars Rover heads uphill after solving 'doughnut' riddle: Researchers have determined the now-infamous Martian rock resembling a jelly doughnut, dubbed Pinnacle Island, is a piece of a larger rock broken and moved by the wheel of NASA's Mars Exploration Rover Opportunity in early January http://www.nasa.gov/jpl/mer/mer20140214/#.uwatlvmsyps 8 comments science