Hi all! I read something VERY interesting this week (last night actually) in a SCUBA diving book of mine. They say that the the angel might nip at one polyp on the coral - BUT then all of the polyps retract - ensuring survival of the coral polyps on the coral colony as a whole.... And if there are a LOT of corals, then the impact is absolutely minimal.... BUT, if a fish like a trigger or parrot fish nips at the coral, it actually eats the WHOLE coral, including skeleton - in which case it causes major damage to the coral colony as a whole.... BTW: the angels only eat the coral polyps flesh....