I just noticed these gray masses on a piece of LR. I don't know when they first appeared, but I want to say it happened pretty quick since I never noticed until now. Or it could be that I didn't notice them during the daylight.
I purchased this tank a couple weeks ago already established.
At first I thought they were some kind of algea or bacteria, but then I noticed that they all have little holes in them at the center.

At first I thought they were some kind of algea or bacteria, but then I noticed that they all have little holes in them at the center.


