This bony core is covered with keratin, much like what our fingernails are made of. Horns get larger as the animal matures, and are not shed yearly. Horns can often be found on both the male and female of a species, though in some species they are only on the male. When comparing horns of males and females, male horns are usually larger. This makes them better adapted for battles over territory or mates.
Horns can be straight or curved.
Most horns have a single point , not the branching pattern of antlers. It serves as an insulator much like fur does. Fur is not as effective an insulator for these water dwelling animals because it loses its ability to insulate when it gets wet. Blubber can sometimes keep an animal too warm, however, especially during times of extreme activity so marine mammals need special ways to release this heat. Seals and sea lions will usually allow it to radiate off their blubberless flippers.