nah, its not xenia. its a sea pen. genus Cavernularia. since this thread is a few months old I'd bet the animal is dead by now, unfortunetly they are tough to keep.
Fishome, I think you are right....I should have looked closer and seen the body off to the right and that it was laying flat threw me off as i don't think that is standard behavior for sea pens.
Cavernularia obesa
I agree, filter feeders do not seem to do well in reef tanks.