Dark round disk & twigs

[Fish.Bum00]

I've looked thru threads, tried blowing and scraping them off rocks but neither will budge.

1) dark tinted disc
2) black twig like growth from crevices on rocks. Can't get a good angle of it in a photo.
Neither look like algea I've seen. Neither have moved. Any thoughts?

 

[Mastiffsrule]

Hi,

sorry, just no way I can make it out. Maybe someone else can figure it out from the description. If it is not moving, growing, or changing in any way at least it should not be anything to worry about. I hope