Mystery Fossil

Data: I found these and others like them in rock deposits eroding from a forested hillside on Cougar Mountain in Western Washington near Seattle. Can you help me identify them? I can't decide if they're gastropods or what. They were found in matrix with numerous clam shells as well. They're very fragile and the stone is soft and brittle when damp. Any help would be much appreciated. Thanks!


Send Ideas to: Colby Hess




  • The pattern on the curved part looks very cephlopod-like. But I wouldn't bet the farm on it.
    ... Douglas S.

  • How about internal molds of the slipper shell, Crepidula princeps?
    ... Barry R.

  • Hi Avril, What is the scale ? It might be silly but can't it be a Cavolinia ?
    Kind regards, ...Sophie V

  • Avril, as others have suggested, these are crepidulids (note that Crepidula no longer includes many species placed there until recently).
    The shells have been decalcified and not replaced by other minerals, thereby leaving cavities.
    ... Andrew G.

  • The hook one appears to be the internal cast of a crepidula or slipper shell.
    ... Jack D.

Return to: