Something is eating my corals

[corper]

Thanks guys! I don't know if it's a worm though. Their are large chunks missing from the corals, I'm thinking a crab. But why now? Nothing new was added to the tank. Maybe it just ran out of it's normal food sorce and now its on the main dish.

If anyone has pics of possible coral eating crabs, I would like to see them. Then I'll know what to look for. Thanks.