The spine, composed of trabecular dentine, is roughly a right triangle in shape, with the hypothenuse concave anterodorsally.
en.wikipedia.org The cusps contain both dentine and enamel, whereas minor projections on the crown, called crenullations, are the result of different enamel thickness.
en.wikipedia.org They comprise a soft pulp surrounded by dentine and covered by a mineralized substance such as enamel, a structure similar to that of teeth.
en.wikipedia.org Dentine can be as hard as the rest of teeth, and is composed of collagen fibres, reinforced with hydroxyapatite.
en.wikipedia.org The scales of sarcopterygians are true scaloids, consisting of lamellar bone surrounded by layers of vascular bone, dentine-like cosmine, and external keratin.
en.wikipedia.org