What is this?

Those are eggs from a snail, more specifically mystery (apple) snails that are sold in pet stores. If they are kept moist from the humidity from the tank and not dipped into water/under water, they have a pretty high chance of hatching.

Apple snails are cool; I miss the one I had. I never saw eggs before though!

I have never seen eggs laid like that except by insects! That's pretty interesting. So what happened to them? Did they survive their incubation period and hatch? How many came out?