Snails are one of the easiest of the exotic pets to keep. Snails should have fresh substrate every week and this should be at least 1-2 inches deep to allow the snail to bury itself as it would in the wild. Mine are rather keen on Peppers, Cucumber and Cos lettuce. They have also eaten apple, nectarine, grapes, banana, peach, plums, etc They will also eat brown bread and moistened dog biscuits. Without this calcium the snails shell will not be very strong and maybe slow to grow.
Snails are also fond of the occasional drop of beer.
A word of warning though, please treat them gently as you can easily damage the new shell growth at the base of the shell. In the west of Africa they are farmed for their meat and their shells. The meat is eaten by the locals, like giant escargot, and the shells are ground up and used in native medicines. In East Africa, giant snails of a number of species are eaten, and in East Africa they are fed to domestic animals, particularly ducks. The brightly and individually coloured Banded snail Ceprea nemoralis is perhaps the most attractive.