>I have another Mystery fossil this evening.  This one is from Washington
>State.  http://www.manandmollusc.net/Mystery_shell_pages/colby-mystery.html
>
>I have a hard time figuring out the ?? shell - but, those of you more
>familiar with fossils might be able to give Colby ([log in to unmask] ) some
>direction.

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 Grebneff
Dunedin
New Zealand
Fossil preparator
Seashell, Macintosh, VW/Toyota van nut
‚ Opinions stated are mine, not those of Otago University
"There is water at the bottom of the ocean"  - Talking Heads

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