Found this on wetwebmedia:
Real Serpents for Stars
I recently purchase two coral banded serpent stars and a colt coral to add to
my75 gallon reef tank. the other night I saw the serpents star grab the colt
coral and start to drag it away. I grabbed the coral and put it back in its
spot. This morning I noticed that the colt coral is missing. will serpent stars
eat these or any other corals, and if so how do I get them out of the tank
without dismantling all my rock?
Yes, some (way too many) Serpent Star species have proven to be "eater uppers" rather than "cleaner uppers"... You've stated an extreme case!
You should have success with baiting them out with something large, meaty, near the inside, bottom, front of the tank after turning out the lights... finally a use for that Y2K flashlight!
I think that I found the culprit that's been munching on my xenias... Now if only I could get him out of the rock.