The rock was captured in the photos taken by Opportunity rover and has been dubbed as 'Pinnacle Island'.
Steve Squyres, NASA Mars Exploration Rover's lead scientist, discussed about the rock during an event held to mark the decade of Opportunity's arrival on the red planet, the French Tribune website reported.
The rock was seen in front of the rolling rover over a few days ago on January 8. However, what has baffled researchers that when they went back to review the panoramic images taken on sol 3,528, a sol is a Martian day, they found no evidence of the rock.
Squyres told Discovery News, "It's about the size of a jelly doughnut. It was a total surprise, we were like 'wait a second, that wasn't there before, it can't be right. Oh my God! It wasn't there before!' We were absolutely startled."
Squyres said that there could be two possibilities behind that. First, while navigating the tricky terrain the rover might have flicked the object; second, the rock might have come on the Martian surface after a meteor impact nearby.
