I have some base rock I picked up months ago, the stuff is awesome by the way John. Anyway, I have places that look like obvious coraline and spots that look just like that picture above. It doesn't seem to harm anything I figured it was basis of coraline propagation or something similar. I had a black cyano outbreak 2 months ago. I treated it and after two weeks it was gone(lets say a month ago it was totally gone). I have spots similar to the pictures above that prevailed through treatment while the other stuff was destroyed as promised I have deemed it harmless myself and that it must be some stage of coraline growth but personal experiences may vary. Just my 2 cents and thanks again John for all of the inverts, rock, and great service!