Greyish stringy thing on rocks?

[soundlemon]

Hey folks,

I setup this tank about half a year ago and recently noticed these weird grey lines growing on my rock. Does anyone know what this is? I even found some growth in my mesh filter sock.

 

[Crabs McJones]

Welcome to R2R! #WelcometoR2R
Does it come off easily or is it encrusted to the rock?

 

[soundlemon]

Thanks :)
From what I can tell it's not encrusting. Took the rock out and scrubbed it with my finger and it's coming off.

 

[Idech]

Thanks :)
From what I can tell it's not encrusting. Took the rock out and scrubbed it with my finger and it's coming off.

Don’t use your fingers. You’ll get micro cuts and risk infection from the bacteria on the rocks. Use a hard brush or even a tooth brush.