I am in the process of starting over my 180. The majority of the rocks I scrubbed clean but a few I put in a large container with the fish and corals. As I am checking each piece for aiptasia and white sponge, those 2 in particular had just taken over, I am finding a yellow encrusting algae. Well, I have to guess it is an algae. When touching it, it feels rough and bristly, I would liken the feel of it to Velcro, rough. I have found this on a rock that is covered in palys. While I hate to lose my palys, I do not want to start with something that is not good. Am I correct, is this an algae? Any guesses anyone. I tried to get pictures but they came out terrible, so did not post.