One of the latest images from Opportunity (mib_color1_rgbstretch-B011R1.jpg) shows tiny spheres which are interesting... but did anyone else notice the several objects which seem to exhibit bi-lateral symmetry? In the upper left quadrant of the picture, two objects appear to be identical in size and shape except that one is on its "back" and the other is on its "belly". They have the characteristic "butterfly" shape of (and I'm no crackpot) VERTEBRAE! In the lower left quadrant of the picture is a third somewhat larger and less well-defined object (above and to the right of the golf ball shape) which also seems symmetrical. True, these objects are very tiny, but are there natural, non-biological forces which might explain such bi-lateral symmetry?