broken chalice

I purchased a Chalice on Sunday and placed it on the sandbed so that it can begin adjusting to the light in my tank. Last night when looking at it, it appeared that some of it was missing but I thought I must be mistaken. This morning when I looked at it, it was broken into multiple pieces.
What is going on?
When looking at the tank, I have never seen any animals bothering it.
My tank only has 2 clowns, 2 small damsels, yellow tail goby, several hermit crabs, a variety of snails, a cleaner shrimp, and one other crab (can't think of name, but it is not in a shell and it is about an inch including legs, so not large). I repeat what could be going on.

 

what do you mean by broken? was the tissue was torn? or was the exoskeleton cracked?
can you get a pic of it?

 

Skeleton was actually cracked. the one piece is now in 3 pieces.

 

Are you sure it was ever 1 piece?

I can't imagine that it would just break apart as the skeleton is usually pretty strong. It may have been that it was broken, but the tissue was holding it together and the stress from the acclimation made the tissue weaken... not sure.

Pic would definitely help.

 

my money is on giant stone crabs