Water snails lay egg sacs, which are usually attached to any surface in the water, such as a plant or a rock. Depending on the type of snail, there can be anywhere between 10,and 30 eggs within them, and hatch anywhere from 3 to 10 days. The egg sacs are clear, and usually you can see the individual eggs within them slowly develop into snails. As far as I know, no snails give live birth, and therefore are never "pregnant", but can lay many egg sacs with little time between them, effectively producing hundreds if not thousands of baby snails within their short lifetimes
