The mantle also extends outward in flaps which reach to the edge of the shell and in some cases can cover the shell, and which are partially retractable. The mantle is attached to the shell, and creates the shell and makes shell growth possible by secretion.

Most molluscs, including land snails, have a shell which is part of their anatomy since the larval stage. When they are active, the organs such as the lung, heart, kidney,