what do you see what should I do?

[Amandry7]

Worried about the back glass of the tank I see a lot of hydroids and learn that its ok to have that but I see a lot of brown spots that are hard to the touch and dint come off as easy as the diatoms dud when they appeared during the cycle
55 gal. About a month or more of cycle...2 damsels 3 cromis...3 brittle worms, 1 bristle star fish 10 turbo snails 10 hermit crabs....

 

[Amandry7]

Thanks