Last night I saw one of my clown fish nip at a piece of highlighter stag and just figured there was something on it like a piece of food but this morning I woke up to find him still nipping at it and the whole 4" frag is bone white.
If you put the coral in the clowns area (especially if Maroon/Spinecheek/Tomato clown) they might move it. Also if you have a pair & they are ready to lay eggs they will move anything in their path.
if it's all white today then as mentioned it was on it's way out...the tissue was RTNing or just peeling off the skeleton which is what the clown was eating.