Help! Can someone identify these structures found in a frog's diet?

Im totally out of your area but, if it could be a terrestrial invertebrate, perhaps its got a crystalline structure (like chitin). If thats the case, take a chunk nd look at it under a polarized light microscope with a rotating stage and substage lighting. The crystalline structure ill appear as colo changes as you rotate the stage and the colrs are absorbed by the polarized planes of light.

Other than that, I have no clue (We look at fossil chitenous material and are able to deduce structures and chemical makeup in plane polarized light).