There are some rather big rock formations inside the Living Seas tanks. They get rather dirty and yucky at times. They don’t clean them inside the tanks. What they do is, they take out the whole huge rock formation, and replace it with an exact replica, while the other one is being cleaned and repaired. They do that so it does not confuse the fish.. and upset them or their environment.
Also, since it is illegal to harvest coral... they create new "coral" buy using dental cement.
Also, since it is illegal to harvest coral... they create new "coral" buy using dental cement.
