New Crocea clam help

[dcw1sfu]

Hey bought a crocea clam and have never owned one before. It small and I have it on the sandbed trying to get it attach to a frag disk. I have dremmled out of the frag disk for it to sit in but over the course of a day it is off the disk sittin in the sand again. From my understanding these should not be sitting right in the sand. Any ideas on how to get this bugger to attach without moving?

I have now placed it in a small Tupperware on the frag disk hoping it attached. This a good idea?