A friend gave me a coral, looks like green palys but don't take my word for it, I don't have a lot of experience. However, I've tried reading about them and some say they're good beginner corals and others say stay away because they'll kill other corals and take over your tank. Not to mention the possibility of killing you if you mishandle them. So please let me know before these things get established whether to keep them or chuck em out and tell my friend they died or disappeared or something. Thanks!