I got a serpent star with my tank about 3 months ago, i believe he is eating my cuc. Ive got alot of shells laying around and today, he was on top of my larger hermit. I broke it up and my hermit is fine. The serpent is setting in a bucket right now. They are kinda creepy too, i really dont want him and im sure that my tank is to small for him and thats why hes after my cuc. He ate my 5 min old nudibranch too.