Cartilage /ˈkɑrtɨlɨdʒ/ is a flexible connective tissue in animals, including the joints between bones, the rib cage, the ear, the nose, the bronchial tubes and the intervertebral discs. It is not as hard and rigid as bone, but it is stiffer and less flexible than muscle.Because of its rigidity, cartilage often serves the purpose of holding tubes open in an animal's body.