"like the old skin that a snake sheds"
Creative Commons Attribution Share AlikeMoulting - Credit: Mike Ferris
Moulting is the process by which a snake sheds its skin, in one continuous piece,  to allow for growth, as well as to remove parasites along with their old skin. Snakes shed their skin by brushing against something hard and rough, like a rock, and creating a rip in their skin. When a new skin is formed beneath the old skin, a rip is initiated in the nose and mouth area. A snake continues to work on this rip until it can shed its skin completely.