Is this red Algae and Is it Dangerous ?

[Sky87303]

No idea when this showed up, but I just noticed it now. Should this be removed asap? What is it? How do I get rid of it? What caused it? My thought is that it might just be oxidation because my water level gets low sometimes. Thank you !

 

[Colin_T]

Red coralline algae, completely harmless, leave it alone.

Coralline algae comes in a range of colours and is part of a marine ecosystem. It's easy to identify because it's hard when you touch it, due to being mainly calcium carbonate.