The Rover was doing some work when one of the engineers noticed this shiny screw like object and now NASA has halted all work to focus in on this shiny metallic looking object. Maybe a screw came loose? Maybe Mars has Silver?
Will post an update once it is available.
EDIT UPDATE :
New information is here http://mysteryhistory.tv/nasa-says-shiny-metal-is-likely-benign-plastic-from-curiosity-rover/