Рог (Rock) = A horn is a pointed projection of the skin on the head of various animals, consisting of a covering of horn (keratin and other proteins) surrounding a core of living bone. True horns are found mainly among the ruminant artiodactyls, in the families Antilocapridae (pronghorn) and Bovidae (cattle, goats, antelope etc.). One pair of horns is usual, but two pairs occur in a few wild species and in a few domesticated breeds of sheep. Horns usually have a curved or spiral shape, often with ridges or fluting. In many species only the males have horns. Horns start to grow soon after birth, and continue to grow throughout the life of the animal (except in pronghorns, which shed the outer layer annually, but retain the bony core). Similar growths on other parts of the body are not usually called horns, but spurs, claws or hoofs.