The rock wasn't eroded as fast as the surrounding material
NASA has weighed in on the shiny object seen in some of the images Curiosity sent back from Mars. This is the second shiny object that caused a stir, the first was a piece of plastic fallen off of Curiosity herself.NASA's experts have explained [PDF] that the latest shiny object, which looks like a door knob, is naturally formed and was created when the softer rock around it was gradually sanded away.
The shiny rock was initially encapsulated in a larger one. However, since it was made up of a different material, it didn't weather away in time, under the action of the Martian winds and sand.
In fact, it's precisely the sand that gives it its shiny appearance, the rock was effectively polished by erosion.
While there were plenty of theories, NASA did say that the object originated from Mars and that was the most likely explanation.
Still, as Curiosity beams back more photos of its surroundings, photos which are available to anyone who wants to check them out as soon as they arrive on Earth, strange rock formations or maybe even weirder things are going to be spotted.