Baby Apple Snails?

[Smokescreen]

I turned on the light in my ACF tank last night, which is also home to some apple snails, and there were hundreds of tiny almost transparent white creatures about the size of a couple grains of sand crawling around above the water line. After seeing two brand new egg clutches on my hood, I thought that perhaps these had been from a previous clutch under the hood that I hadn't noticed, but looking at pictures, I'm not sure this is the case.

If not, what on earth are these little things? They're much too small to get a picture of, and it seems like overnight, many of them have disappeared. Any ideas?