I glue all my frags down with superglue gel. If I don't, the snails and hermits knock them off and they end up on the sand. They come off with just a pull, actually. So if the coral isn't happy, it can be moved pretty easily.
And BTW, I had a half black dwarf angel in my reef, and it ate zoas, brain, birdsnest, just about any kind of coral I had. And I feed everyday. Had to take half the rock out and redo the rock scape in order to catch it and put it in qt until i got a FOWLR
tank going. He lives in the FOWLR