I've seen all three species of Atlantic  Crepidula on any hard
substrate they can find, shells, rocks, plastic buckets etc.   and
also on  horseshoe crabs, which they can be quite numerous upon and
get quite large- presumably the movement and feeding activity of the
crab may offer some kind of metabolic advantage...... Crepidula plana
is the only species I have noticed inside the aperture of dead shells
of every size.

On 1/5/23, David Campbell <[log in to unmask]> wrote:
> I've seen similar occurrence of *C. plana* on empty bivalve shells.
>
> On Thu, Jan 5, 2023 at 9:00 AM Callomon,Paul <
> [log in to unmask]> wrote:
>
>> Folks,
>>
>>
>>
>> Some dead-trawled pairs of Quahogs (Mercenaria mercenaria) I found in our
>> collection have the same two *Crepidulas* on them as we usually find on
>> crabbed gastropod shells (*C. plana* on the inside, *C.
>> fornicata/convexa*
>> on the outside). I’ve never seen this combination on a dead bivalve, and
>> wonder if it’s a known thing? I’d heard previously that *C. plana* fed on
>> the crab’s exudates, which accounted for it only being found in crabbed
>> shells, so clearly that can’t be the whole story.
>>
>>
>>
>> Paul Callomon
>>
>> Collection Manager, Malacology and General Invertebrates
>> ------------------------------
>>
>> *Academy of Natural Sciences of Drexel University*
>>
>> 1900 Benjamin Franklin Parkway, Philadelphia PA 19103-1195, USA
>> *[log in to unmask] <[log in to unmask]> Tel 215-405-5096 - Fax 215-299-1170*
>>
>>
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>
>
> --
> Dr. David Campbell
> Associate Professor, Geology
> Department of Natural Sciences
> 110 S Main St, #7270
> Gardner-Webb University
> Boiling Springs NC 28017
>
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