Hi, I've had all the xenia kinds, and yes they can do that, and then you just find them in another location in the tank, but most likely they are upset and croking. How much iodine do you add, and what do you feed them. They love "golden pearls" I've noticed that they quite easily get stung, and are fairly touchy except for anthelia which is quite hardy. Also sometimes just changing the flow helps, but in some tanks for some reason, it is just imposible for those tanks to house any xenia. So good luck, and I hope it isn't melting away on ya. Good luck, ali:happyfish