xenia, star polyps, zoas, palys, kenya tree, and mushrooms are just a few that will never be in a tank of mine ever again. my first tank almost 10 years ago I was all excited I got a small kenya frag that was on my first piece of live rock. Within 2 years it was probably about the size of your wrist at the base and took up about a quarter of a 75 gallon tank. It started dropping off limbs that were starting to propagate and grow elsewhere in the tank. That was when it was time for him to go. Same with the xenia.