hmmm, i dont know why it does this but the top umbrella area of my leater coral (disk?) fell off by itself too. i put the disk on a rock and it grew a new stalk and the stalk grew a new umbrella. maybe natural asexual reproduction?
Well, the top of my Sarco didn't come off, the whole stalk was laying over @ the base. I forgot to mention that it was waxing over, cleaning itself I guess. Today when I got home from work the top was clean & the stalk was upright eating the 150 HQI lighting again. One interesting note. This coral happend to wax over or clean itself in cycle w/ the full moon. I will try to remember to watch next month for this again. My fish room is glassed in on one end. The glass wall & sliding doors face south so sun & moon are a real nice touch.