Serpent stars... tell me about them.

I am about to put an order in for inverts at the local frag swap in a couple weeks. Thinking about getting a serpent star. Can you tell me anything I should know about them? Mostly worried about if they will knock coral over (is it common anyway), will they harm my small hermits... or my fish, and all-around, how are they in a reef tank?



I really dont have a NEED for one, I just like they way they look.