I saw some time-lapse footage on one of those discovery channel shows (life, wild pacific, etc..) and they showed what happens when corals attack (they should make a show called that!). The coral feeding tentacles begin to stretch out and latch on to the invading coral. It then covers the problem area completely, enveloping it and I believe eating it. I believe this usually takes place at night and the next day a piece of the loser coral will be skeletonized.
Micah
Edited by Sculpin - October 11 2010 at 9:01pm