Tulip Snail? Whelk? Clam Eater?

[sunshine123]

I’d like to get another clam. I put a small one in a few months ago and the next morning gone. Shell picked clean. When it was in an open mushroom box for a few days nothing bothered it. Put it on the substrate GONE. Wondering if this guy could be the culprit. Would like an ID. Polished, smooth shell. Foot is beige and body white. Spends most time under the stand. Comes out when tank is fed. It's about 2" long and I have had it for a year and a half.

 

[DSC reef]

Resembles a babylonian snail, will eat tridacnid clams.
@Lovemyreef2015 @KJ

 

[Lovemyreef2015]

Yep,that's what it is. Get rid of it if you want to keep clams.