A horn is a permanent pointed projection on the head of various animals that consists of a covering of keratin and other proteins surrounding a core of live bone. Horns are distinct from antlers, which are not permanent. In mammals, true horns are found mainly among the ruminant artiodactyls,[not verified in body] in the families Antilocapridae (pronghorn) and Bovidae (cattle, goats, antelope etc.). Cattle horns arise from subcutaneous connective tissue (under the scalp) and later fuse to the underlying frontal bone – Jigged scale horn

One pair of horns is usual; however, two or more pairs occur in a few wild species and in some domesticated breeds of sheep. Polycerate (multi-horned) sheep breeds include the Hebridean, Icelandic, Jacob, Manx Loaghtan, and the Navajo-Churro.

Horns usually have a curved or spiral shape, often with ridges or fluting. In many species, only 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). Partial or deformed horns in livestock are called scurs. Similar growths on other parts of the body are not usually called horns, but spurs, claws, or hooves, depending on the part of the body on which they occur.

On humans

Cutaneous horns are the only examples of horns growing on people.[4]

Cases of people growing horns have been historically described, sometimes with mythical status. Researchers have not however discovered photographic evidence of the phenomenon.[5] There are human cadaveric specimens that show outgrowings, but these are instead classified as osteomas or other excrescences.[5]

The phenomenon of humans with horns has been observed in countries lacking advanced medicine. There are living people, several in China, with cases of cutaneous horns, most common in the elderly.[6]

Some people, notably The Enigma, have horn implants; that is, they have implanted silicone beneath the skin as a form of body modification – Jigged scale horn

Human uses of horns

Horned animals are sometimes hunted so their mounted head or horns can be displayed as a hunting trophy or as decorative objects – Jigged scale horn
Some cultures use bovid horns as musical instruments, for example, the shofar. These have evolved into brass instruments in which, unlike the trumpet, the bore gradually increases in width through most of its length—that is to say, it is conical rather than cylindrical. These are called horns, though now made of metal.
Drinking horns are bovid horns removed from the bone core, cleaned, polished, and used as drinking vessels. (This is similar to the legend of the cornucopia.) It has been suggested that the shape of a natural horn was also the model for the rhyton, a horn-shaped drinking vessel.[11]
Powder horns were originally bovid horns fitted with lids and carrying straps, used to carry gunpowder. Powder flasks of any material may be referred to as powder horns.
Shoehorns were originally made from slices of bovid horn, which provided the right curving shape and a smooth surface.
Antelope horns are used in traditional Chinese medicine.
Horns consist of keratin, and the term “horn” is used to refer to this material, sometimes including similarly solid keratin from other parts of animals, such as hoofs. Horn may be used as a material in tools, furniture and decoration, among other uses. In these applications, horn is valued for its hardness, and it has given rise to the expression hard as horn. Horn is somewhat thermoplastic and (like tortoiseshell) was formerly used for many purposes where plastic would now be used. Horn may be used to make glue.