can someone again please post a pick of bubble alge. i have had my PC lights for almost 6 months and i noticed 3 small round balls on a rock. its the only place i can see them. they are about the size of a B.B. it is dark brown in color. the thing is they feel very hard. i tired to pop it and it took a lot of pressure and now i am left with a shell on the rock. Is this bubble alge?