I got a new piece of live rock. 4 days later noticed somthing crawling out of a hole in the rock. It is a really dark blue almost black. it is almost oval shaped (1/2 " wide and 1 1/2" long) it has a shell like white stripe down its back, antenna about 1/4" long. I suspect it is a type of Nudi branch or sea slug. but maybe somone could tell me if it is reef safe. or what it eats. a name. so I could learn more about it. Thank you in advance for any help you may provide. ~mark