Can someone ID this brown stuff?

[PBnJOnWheat]

Super hard substance I have to use fingernails to scrape it off. My flipper max can’t even do it... any recommendations? Hard to get cool pictures with this stuff everywhere.

 

[JGT]

Super hard substance I have to use fingernails to scrape it off. My flipper max can’t even do it... any recommendations? Hard to get cool pictures with this stuff everywhere.

Pics without blue light please. Not sure what you’re referring . Sounds like coralline algae but you pics aren’t clear.

 

[PBnJOnWheat]

Pics without blue light please. Not sure what you’re referring . Sounds like coralline algae but you pics aren’t clear.

It’s brown really but hard as coralline.you can see where I’ve tried to remove around it but it just doesn’t come up D:

 

[JGT]

It’s brown really but hard as coralline.you can see where I’ve tried to remove around it but it just doesn’t come up D:

Can’t tell, is that on the glass ?