NASA announced this week that it has solved the mystery of the “jelly doughnut-shaped” rock that suddenly appeared in front of the Mars rover Opportunity earlier this year. The small white-ish rock with a deep red center was dubbed “Pinnacle Island” by scientists at NASA, who say the rock wasn't there one day, and then 12 Martian days later, it showed up in images that Opportunity sent back.
While NASA took the discovery in stride, the information instigated some outlandish speculation from people outside of the space agency, and one “astrobiologist” even sued NASA for failing to expedite an investigation of the rock. (He demanded 100 high-resolution photographs of the anomaly, which he was sure was a “mushroom-like fungus, a composite organism consisting of colonies of lichen and cyanobacteria, and which on Earth is known as Apothecium.”) The space agency, for its part, maintained that the rock was either a close call with a meteor or the result of something Opportunity did.
It turns out that NASA's latter speculation was correct: Pinnacle Island is just a small piece of a larger rock that broke off when Opportunity drove over it. According to the Jet Propulsion Laboratory, "Once we moved Opportunity a short distance, after inspecting Pinnacle Island, we could see directly uphill an overturned rock that has the same unusual appearance. We drove over it. We can see the track. That's where Pinnacle Island came from."
Although the air of mystery has been diffused, the rock is still quite interesting to NASA scientists. According to the Los Angeles Times “Opportunity's instruments have revealed that [Pinnacle Island] has high levels of sulfur and manganese, water soluble ingredients that may have been concentrated in the rock thanks to the action of water." It seems that Opportunity is living up to its name for NASA scientists, even in the rocks it drives over.