"Experts said they were “completely confused” by both the origins and makeup of the object, which is currently being investigated by Opportunity’s various measuring instruments."
"Astronomers noticed the new rock had “appeared” without any explanation on an outcrop which had been empty just days earlier. The rover has been stuck photographing the same region of Mars for more than a month due to bad weather, with scientists at the Jet Propulsion Laboratory (JPL) in California monitoring the images it sends."
"We had driven a metre or two away from here, and I think the idea that somehow we mysteriously flicked it with a wheel is the best explanation," Squyres said. Squyres is the lead Mars Exploration rover scientist.
Where do you think this rock came from? Unserious answers welcomed.