Clams on Mars?

See update 3/15/4 at end of page

Here are a couple of pictures from the Opportunity microscope following by an image of a clam shell still stuck on the outside of the Frass Meteorite.  There are several "clam" looking items in this picture.  At the top left is on object that is not exactly circular and has a protrusion on one side.  Some clams look like this.  At the top right is an object with a crease down the middle.  Also find several round objects that could be stones or something else.

Here is a picture of the "dirt" from the Frass Meteorite to compare with the "dirt" shown above.

Here is a new picture that came in on Sol 48.  Isn't that a shell fish half in the lower right hand corner?  This was taken in the "blueberry bowl."  And what are all the other things in this picture.  Could they also be different type of shell fish?

http://marsrovers.jpl.nasa.gov/gallery/all/1/m/048/1M132444465EFF05AMP2956M2M1.HTML