Antlers

I found this antler on the lawn by our place. It's not too surprising, there are lots of deer around (black tailed, a kind of mule deer) and this is the time of year they shed their antlers.

Antlers (e.g. deer, elk, moose) are bone that grows out of the skull. Usually only males have them, although both male and female caribou have antlers. Horns on the other hand (e.g. sheep, goats, bison) are covered in keratin, the same material as our fingernails, and usually aren't shed. When antlers are growing, they are covered in skin, known as velvet, that provides oxygen and nutrients to the growing bone. Once the antler is grown it loses the skin and the bone dies.

Shedding the antlers is triggered by the length of the day and testosterone level. Special cells called osteoclasts dissolve the bone at the base allowing it to detach. Judging by the pink base (presumably remnants of blood supply) I think this was quite recently shed.