White, horny substance found in the external skeleton of lobsters , and many insects; in internal structures of some other invertebrates; and in some fungi, algae, and yeasts.
It is a {{link=polysaccharide">polysaccharide , the monomer unit being glucosamine. It is used industrially in purifying wastewater, thickening and stabilizing foods and pharmaceuticals, and sizing and strengthening paper, and as a wound-healing agent, an ion-exchange resin , a membrane for industrial separations, and a binder for dyes, fabrics, and adhesives.