Eggshell membrane or shell membrane is the clear film lining eggshells visible when one peels a boiled egg Chicken eggshell membranes are used as a dietary supplement Composition Eggshell membrane is primarily composed of fibrous proteins such as collagen type I Eggshell membranes also contain glycosaminoglycans such as dermatan sulfate chondroitin sulfate and sulfated glycoproteins