I have done some research but would rather post a picture and see what the consensus is. Tank is 2 years old great coralline algae on over half of my rocks. The other half was added 6 months ago and is starting to grow. Under blue lights you are starting to see the red spots, however under white lights they really stick out as the pictures show. It was only on this piece showing in the picture however I’m starting to see small spots on larger rocks. I have tried to brush off but doesn’t. Is this just a form of coralline or is this a nuisance? Thanks for any help in advance.