that's a pretty big jump. how do you know it will eat coral? can you ID it down to species? if it is indeed a nudi, they may eat anything. some eat algae, others eat sponge, bryozoans, gorgonians, etc. there's a nudi made to eat just about anything in the ocean.
looking at the antennae and the rounded frilly appearance, it looks (to me) like it may be Cypraea moneta, the money cowrie, which is a great algae eater.