Horns are pointed growths on the head of various mammals. They consist of a core of living bone covered in a layer of horn that is made up of keratin and other proteins.
Horns start to grow soon after birth and they continue to grow throughout the lifetime of the animal.
In many species only males have horns and they can come in various shapes and sizes. They can be simple upright horns, twisted, spiral, recurved, lyrate or long curved and they often have ridges or fluting.