I had similar looking stuff on my rock. Was told many different things; one of them being green coraline which I tend to agree with. Eventually most of it turned into either purple coraline or cleared up. It happened around 2-3 months after starting up and now i'm 5 months in. I've since added a gfo reactor which may have helped out but not sure. I did make a post about it way back if you want to match up my photos and see but it looks pretty darn close to what I had.
Anyways hope it clears up or turns purple soon. Good luck!!