What are the horn like protrusions on the head of a giraffe called?

Ossicones are horn-like (or antler-like) protuberances on the heads of giraffes, male okapis, and their extinct relatives, such as Sivatherium, and the climacoceratids, such as Climacoceras. Only giraffes and okapis have true ossicones (as opposed to horns or antlers). The base that a deer's antlers grow from is very similar to an ossicone. Ossicones are similar to the horns of antelopes and cattle, save that they are derived from ossified cartilage,and that the ossicones remain covered in skin and fur, rather than horn. Antlers (such as on deer) are derived from bone tissue: when mature, the skin and fur covering of the antlers, termed "velvet," is sloughed and scraped off to expose the bone of the antlers.