I can try to get better pics if need be. But it looks like red wiry algae but it’s super short. And off of it grows greenish brown algae that looks like hair algae. I get my tooth brush and the green stuff comes off but leaves the red turf like algae behind. No matter how hard I scrub it doesn’t come off. Not to mention my clowns attack me relentlessly while I try to do so lol.