Yes its mouth is open. Havnt added anything to my tank since I got him except a colt coral,on the other side of the tank. It is no longer emmiting anything but the stuff is all over my tank and even caught up in my sallylightfoots legs as well as trapped on my rock. There are only about maybe 10 or so tenicles that are shruken up. Would it be best to remove it?, could it mess anything in my tank up? I dont have a Q-tank so my only option would be to dispose of it.