Snail or something else living in my rock?

[CarChase]

This came out from a crevice in a piece of live rock. I’m not sure what it is a snail? It came out for a minute and went back in. I’ve never seen it before ( that rock has been in the tank for about 2.5 months. It was purchased from LFS. It appears to have a shell that looks something like a mussel shell. Anyone have any ideas?

 

[Lovemyreef2015]

It's a stomatella snail. They like to come out at night mainly. Good cuc