Well Macten, it is hard to really see what this is. One direct comment for us, as we look at this - in the photo, one can also see the wheel tracks of the Rover. I sometimes use the tracks to try to make a guess as to the size of whatever i am looking at in these Rover photos, because it is always hard to know true size of photo objects in most of these. I know a Spirit/Opportunity wheel is about 10 inches in diameter. So, in technical pics of the wheels, the tread width looks to be about half that.
So, if we use 5 inches for the tread width on the surface in the photo, and compare it to the width of "sculpture" you posted, we can see that it is about same width, give or take an inch or two. It is a pretty small piece, what ever it is, rock or sculpture.
