What are these?

[ReeferNoob77]

I have found these disc things on my sand bed not sure what they are. Guessing would be from snail shells somehow they have a swirl design on one side and color pattern on another and are hard like stone.

 

[saltyfilmfolks]

turbo snail discs. its the little door they open and close at the opening of the shell

 

[ReeferNoob77]

Thank you,. Poor snails

 

[lauderdalestunner]

Operculum