Hi...I am new to this community. I was referred by InLand Ocean. Unfortunately, they are out-of-business so I can't go to the store and inquire about our bubble coral. I have done some reading, but I can't find an answer to my dilemma. The edge of the skeleton of our bubble coral has a "black moss" growing on it. It just started. Is this a sign that our bubble is dieing? Is it a form of algea, and is it harmful? I would appreciate anyone who knows the answer to please advise. Thank you. Ann