antlers are found on members of the deer family (Cervidae). They consist of bone and are shed each year. New antlers grow each spring and are covered by skin (called velvet) which has blood vessels that carry nutrients to the growing antler. In the fall of the year the skin dies and is rubbed off on bushes and saplings. Antlers are typically found only on males, except in the caribou.
These are distinct from the permanent horns of species such as cattle, sheep, and goats. Composed of bone, not horn (keratin), they grow anew each year from pedicies, which are permanent outgrowths of the frontal bones of the skull. They are shed in September/October and new growth starts almost immediately.