Enormous Molluscs that have grown fat on a diet of cave moss and carrion. While their grotesque appearance and lumbering single-mindedness may be intmidating to unarmed newcomers, they're not nearly as tough as they look. Indeed, they are a wonderful source of food. Snail meat is said to be nourishing and delicious - at least by those in the adventuring trade.
Giant Snails are mostly encountered in the upper levels of Mount Grimrock. They are slow and incredibly stupid, but they have been known to kill newly arrived prisoners on occasion.