From what I saw it was almost green. Not sure though because I have a few different things growing on my rock or at least living on it. I have at least one green serpent starfish, lots and lots of spaghetti worms, at least one 2'' bristle worm which is creppy as all get out. But then there are these other things. They are thicker than the spaghetti worms, thinner than the bristle worm and they are tan,brown, and sometimes a light shade of green with small what I like to call spikes on them. Ill try and catch another one soon but I have no idea what they are.
In a way they almost look like serpent starfish tentacles but when I took it out there was no resistance and it wasnt attatched to anything.
I know for a fact its not nudibranch. Googled it and nothing in my tank resembles that.