Living algae plant like things on glass

[Crunchycrouton]

I’m not to worried about this but would like to know what they are. They move in the water current and are attached to my tank glass. They have little arms like hydra but don’t branch out to reproduce and are more flimsy. If I don’t clean my tank walls the tank will seem foggy because of it. It creates a white film on the glass.

 

[Fishiemang]

Biofilm.

 

[Crunchycrouton]

Biofilm.

Ok, thank you.