Your Mystery Snails are Pomacea Bridgesii, aka "Brigs" ... a species of Apple Snail. You might want to go to this URL, <www://applesnail.com> to learn more about them. They don't eat live plants, they eat the decaying plant materials, fish food, and algae. They are fascinating to watch. If you let the eggs stay above the water but well humidified, the babies will hatch and move down to the water and begin to eat ... the adult snails carry infusoria in their gut and excrete it with their poop. Infusoria is the perfect food for baby snails, thus the babies will be well-fed. I have watched day-old and older baby Brigs eating the eggs of pond snails (which will eat plants), which helps keep them under control.
I remove Brig clutches after a day or so, when they have hardened, to a hatchery (a piece of damp sponge in a cut down plastic butter tub, floating in a 10 gallon nursery tank), and when the hatchlings begin to move about, I drop them into the Nursery.
Patricia