This tank has been set up for about a year and tonight I looke over and What do I see..... My best quess is Tritoniopsis elegans, Any body want to give me another Idea?????? Perhaps this is Why my leathers have not been growing soo fast. FULL EXAM TO FOLLOW.
Uh Fragman, you did positively identify that nudibranch. They are predatory on soft corals. They are possibly limited to the ones we call "Sinularia". It's very unlikely that you have only one. They are quite prolific and are capable of completely wiping out a soft coral, leaving a white pasty powder in its place.
Find the coral that they are feeding on and inspect it very closely. Look on the coral, near and under it. Lift the rock that the coral is attached and look beneath it. Get every one of them out.
I did Id the nudi, and did erarticate it. the Sarco that it was feed on was slightly damaged on one side under the crown. This is consistant with all that I have read and I am continuing to watch the coral. The next day when the lights came on the coral was already looking much better, but I will continue to watch it in the coming weeks. Thanks for the concern.
Buy the way this thing was an awesome liiking creature, I hated destroying it but...