What kind of snail?

Pond Snail. I kinda like them as they help out with little bits of food. They are also a good indicator if you are overfeeding or not. If there's a lot of them, too much food.
 
They're pond, or more correctly bladder snails. They will multiply fast if there is extra food available. Depending on the fish you keep they may be food especially if you help them get the idea by squishing a few against the glass. You can try trapping them on a lettuce leaf to remove them the next morning. I don't mind a few but extras become loach snacks. They won't eat healthy plants...usually, lol
 
The big one is a Bladder Snail - not a Pond Snail which it is often mistaken for. If there's enough food lying around in the tank, they can become a problem. The two smaller ones look like the Bithynia species that pop up every now and then.
 
AquariaCentral.com