My Xenia was closed up today all day I've never seen it stay closed so long. I know it's healthy because it has more then quadrupled it size over a 5 month period. Is it to close to my bubble coral about 6-8 in apart) could it have stung the Xenia?
First off, bubble coral does have sweeper tenticles that will sting close corals.....and these can go pretty far. Check it out at night with a flashlight. How long have these two corals been sharing close space?
Also, I'm assuming no other changes....lights, large water change, dosing changes, any treatments, etc.