Stuff growing in fishless tank

I've been cycling my 10 gallon tank for 10 days now. I added ammonia, and last I checked I have 1 ppm of ammonia and 0 nitrites. However, this morning I awoke to find some interesting looking mold? something growing in my tank. There are a few spots of it on the glass, usually in a small circle, pale greenish in color with small floating tendrils that stick out into the water.

Is this normal? Do I need to change the water more often? What is this stuff?

Nope, there are no lights in the tank. (I haven't even bought the light bulbs yet.) There's the lights that come on when I'm there in the evening, but I doubt they are strong enough to do anything like that. It's not in the sun at all.

Would a water change help?

Is the stuff dangerous/harmful at all? There is only very little of it. Could I scrape it off and let the filter get it and be all right?

Yeah, I thought it was weird too. I can only guess it was in the gravel. I doubt it was on the filter or the air bubble wand.

I shall scrape it off tonight and do a partial water change.