Originally Posted by kdpuffer
Agree brittlestar and nudibranch, brittle stars are harmless but the nudi could be bad news. I am nowhere near an expert on nudi's but pretty much all are bad. They have very specific food they eat and that's all they eat so once it's gone they starve, lots eat a specific type of coral.
I agree with kd, that looks like it could be a zoa eating nudibranchs. They look like the zoos that they prey upon, to mix in undetected.