Grey sludge ID

[Tigerchuffs]

I’ve got spots of grey sludge On my live rock. I initially diagnosed it as cyano but after three cycles of ChemiClean with no results, I took one rock out and scrubbed it with a metal scrubber in a water H2O2 solution. It seemed to dissolve/break up the grey spots on that rock. The spots don’t come off easy, tried with a tooth brush while vacuuming and didn’t do much. I’d like any of your opinions on it. What I should do. Etc. thanks all!

 

[Tahoe61]

Coralline comes in a variety of colors and growth forms.

 

[Tigerchuffs]

Coralline comes in a variety of colors and growth forms.

Ok so it’s probably just coralline algae then? Pfeww!