Vermited snail?

[jabberwock]

I have them in my tank, but this seems very coiled, and was at the top of the tank. Firmly attached and hard. About 4 mm across.

 

[DSC reef]

That would be a vermetid

 

[Lovemyreef2015]

+1^^

 

[jabberwock]

Thank you. Thought so, it was just in a weird spot. Almost at the water line, and attached to the back of the tank.