Pest aquatic snails are most commonly ramshorn snails, tadpole snails and turret snails. Ramshorn snails (Planorbis spp.) have flat, spiral shells and most are small (less than a quarter-inch across). Tadpole snails or pond snails (Physa and Physella spp.) have bulbous, translucent-brown shells up to a half-inch long. They lay their eggs in distinctive jelly-like clumps. Turret snails or Malayan livebearing snails (Melanoides tuberculata) have conical shells up to an inch long with purple flecks. They are nocturnal and prefer to burrow through sand, but are sometimes active by day.
A decent article on snails from Neale Monks Ph.D.
Read more here – Fish Channel.com