What if a rock that looked like a jelly doughnut suddenly appeared on Mars? That's just what happened in front of Mars rover Opportunity last month. Researchers have since determined that the "doughnut" is a piece of a larger rock broken and moved by the rover's wheels in early January.
FULL STORY: http://science.nasa.gov/science-news/science-at-nasa/2014/14feb_doughnut/
