Clam? Bivalve? Satan?

[mwil79]

So found this attached to my snail, reacts to light similar to a clam. Scared to sleep.

Any idea?

 

[NashobaTek]

Looks like a clam of some type

 

[WVNed]

Godzilla larva. You can see the teeth forming. It's too late already. Your entire continent is doomed.

with a vermetid snail on top just for fun

 

[Sharkbait19]

Agree with the above. Clam and a vermetid.