Okay, while browsing the JPL website, I came across this photo taken by the Mars rover Opportunity... Here's a link to the page: http://marsrovers.jpl.nasa.gov/gallery/all/opportunity_m061.html
I thought the exact same thing when I saw it. Maybe Men in Black was right when they said they held the patents to a few inventions from other planets. Phillips head screws are actually a Martian technology!
I think this is the best theory yet! "Oops, I did the calculations in feet, but I programmed the lander in meters!! Whoops!"
Could it be a dust cover on the rover its self? If u go to the site and hover over the images it gives a breif description EDIT:Opps i didnt scroll down when going to the site. It gives the same description at the bottom
more here: http://marsrovers.jpl.nasa.gov/gallery/all/opportunity_m055.html Dorza is right: "Microscopic Imager dust cover commanded to be OPEN."