Sorry I can't help you with your question about if you should scrape them or not. But I read your message last Friday because I noticed a couple of dozen white spots on my glass in different spots last week, and we figured out what they were yesterday. They are snail eggs. I have turbo snails and nasssarius snails in my tank and we watched one of the nasssarius snails moving down the back glass and leave a trail of 12 white spots behind it. Also, after that I noticed about 20 white spots on my themometer where about 5 turbo snails had been congrigated the day before. The ones on the thermometer look more like little sacks than the ones on the glass which just look like round spots, so I think they may actually be from the turbo snails. I am going to leave them on my glass and not scrape them in the hopes that they will hatch out and I can sell them to one of my local pet stores later when they get big enough.