Definitely a pond snail. The are also known as tadpole snails, and bladder snails. They are the most common snail hitchikers on plants. I consider them harmless to beneficial. Some consider them pests.
They lay clear, jellylike, egg masses on plants. One snail is all you need to have babies, though if you have more than one you may see them mating. Mine lived through cycling my tank. I don't make pains to care for them, but I don't purposely kill them either. They breathe air, carry a bubble of air with them, and sometimes take a quick ride to the surface. They can also crawl upside down on the underside of the surface.
I did have an initial population explosion when my tank was cycling, but once I added fish an equilibrium was reached. They eat algae. If the algae is well adhered to the plant they may eat some of the plant as well. I don't have a problem with this. To me they are just part of the balancing act that is plant and tank care.