White Fungus On glass and overflow

[Munchkin041804]

I'm noticing what appears to be white fungus on the back glass of my aquarium and in my overflow box. What is it and why did it appear. The water conditions are perfect and I do a large water change every other week. I've had the tank for a year & have never had issues before. Will this harm the aquarium?

[melosu58]

Without a picture it`s hard to say but I would guess it is some type of sponge. I have them in my tank all different colors.

[Munchkin041804]

I attached some photos, not sure how well you can see them. I normally leave the green algae on the back glass for my sea hare but if it is fungus should I start scrapping it off?

[melosu58]

Still hard to say. I would err on the safe side and scrape it off. I still think it`s a sponge but cant be sure.