Blow on it with a (new for fish only) turkey baister...if it lifts up like a carpet it is cyano bacteria..we will help you from there.
If it is hard like the rocks, and can't even be scraped off...it is coraline algae. A good type.
Fuzzy red..mmm, I am not sure. I have some
velvet looking red algae but it is hard so it is a type of coraline.