Help with a sarcophyton

I've never heard of a snail doing something like that. It's odd that the snail even climbed up the coral. Are you sure the leather was ok before the snail did this? Snails like Turbos, and Astreas eat algaes, they're herbivours, so it seems the only reason it would climb up the leather was if there was algae growing on the side of the leather. And there would only be algae on the leather if it wasn't doing well. Other then that I don't know. One thing to look for with leathers is there is a nudibranch or some kind of coral parisite that will bore into leathers and eat them from the inside and lay eggs. I've never personally seen it, but have heard of it. Look the coral over real good and look for a hole possibly on the back side of it. Other than that, leathers are ussually real easy corals, and I don't know what else could be wrong. Maybe someone else can help with more info. Good luck.