Ok here it goes...I added a purple urchin to my tank Friday. It has been doing good, going all over the tank and so much fun to watch. Any way, I git up this morning and was drinking my coffee and watching my tank and i noticed that it has eat LOTS of coraline off of my big rock! I have big white patches all over the rock now from where it has eat the coraline. Is this normal?? Should I take it back to LFS? I am not sure what to do. Its beautiful, but dont want my coraline gone. Any suggestions?? It does not seem to be bothering any of my corals either. Just suprised:cursin: