Need Help with Critter ID

[Ain't No Tang]

I have no idea what this thing is. I found it buried under some sand near my Derasa clam. Is this a snail or mussel of some kind? Is it harmless or should I remove it?

 

[Webslinger]

snail. good cuc

 

[KJ]

I have no idea what this thing is. I found it buried under some sand near my Derasa clam. Is this a snail or mussel of some kind? Is it harmless or should I remove it?

Snail operculum.

 

[kyleinpdx]

KJ is correct, this is the "trap door" of a long dead snail.