What about cobbles they've seen everywhere?

"Ever since the start of the mission, we've seen lots of little rocks on the plains - rocks we have been calling cobbles -- and we've never really gone and looked at one -- it's been on our to-do list for a long time and we figured we'd get around to it sooner or later -- and we figured they would probably be little pieces of basalt," explained Squyres. But Heat Shield Rock, as this target was dubbed, had another story to tell.

"We went [to the area] to study the heat shield of course and we actually spent a couple of days studying the heat shield before we even realized there was a rock there," Squyres elaborated. "We said, 'Yeah alright, we ought to check this out.' We looked at it in more detail with the panorama camera (Pan Cam) and realized that this is a very strange object. It had this very bizarre pitted texture. And then when we looked at it with the mini thermal emission spectrometer (mini-TES), the only thing that made sense was that it was made of metal. To mini-TES, it looks like the Martian sky, because it's reflecting the sky which is what metal does in the infrared, and so that gave us a hint it's metal and then we said, 'We've really got to check this out...

...Rover-team scientists are wondering now whether some of those cobbles they've been seeing here and there on the Meridiani plains are also meteorites. "We've been seeing lots of cobbles out on the plains, and this raises the possibility that some of them may in fact be meteorites," Squyres said. "Mars should be hit by a lot more rocky meteorites than iron meteorites," he added. Opportunity's find does have some impact the MER team's science agenda. "It does raise the possibility that meteorites may be significantly more common than we thought -- and we had this on our to-do list anyway -- and so this sort of bumps that task up higher in priority," Squyres said.

So there may be a lot of these meteorite fragments. Time will tell. Also, Oppy is heading south toward what I think they are calling "etched terrain." I suspect we will find some interesting rocks there that will add to the story.