Yup you have eggs!
They might become fish food, if you want to raise them (provided there is food) you can put a fine mesh plastic *cage* around them. Let the sand hold it in place.
Sorry. Did a quick search. I guess I have Nassarius snails and astraea snails, the nassarius snails stay under the sand bed and only come out after lights out, and hardly ever see them on the glass.
At night I have seen a hitchhicker. Tiny little snail, I think it might be an olive snail, but he's only about 1/4 inch if that. Would be surprised if my puffer hasn't ate him yet.
Before you go and add that mesh you might want to do a little research on whether or not there's a planktonic stage for these Nassarius snail eggs in particular. If so, you might be wasting your time. (let's hope not) GL.