Antlers are more than just decorations. The fastest growing bones in the animal world, they serve as weapons, snow shovels, pedigrees for parenthood, air conditioners, and gigantic hearing aids.

All males in the deer family, Cervidae, including elk, moose, and caribou, grow antlers. Caribou females are unique in having antlers, though theirs are slightly smaller than those of their male counterparts.

Beginning their formation in utero, the two circular patches from which antlers develop are called pedicles. Testosterone surges after birth kick-start final pedicle production as well as the process known as endochondral ossification, or antler growth, which starts at four to six months old.

All antlers grow at a breakneck pace—some at rates of up to an inch a day. In early spring, hormones trigger the release of an insulin-like substance that stimulates cartilage growth. That velvety coating you see protecting the antlers is actually packed with blood vessels, enriching the bone with oxygen and other nutrients and speeding its development.

This rapid growth also benefits antlered animals in hot weather, creating a built-in air conditioning system. The vessels surround the antler with warm blood, which, when cooled by outside air, brings down the animal's body temperature.

For the bucks and bulls, towering racks signal to females that the animal is healthy and able to both find food and draw extra calcium from his bones, making him genetically desirable.

And that's not all antlers do. A study published in the European Journal of Wildlife in March 2008 concluded that moose antlers act like hearing aids, directing distant sounds to that creature's very large ears. Using trophy antlers and a sound meter, a Cleveland State University scientist found that antlered moose had more sound sensitivity than those without—up to 20 percent more—allowing them to hear faraway predators or females. He concluded that "the palm [the widest part] of moose antlers may serve as an effective parabolic reflector, which increases the acoustic pressure of the incoming sound." It's not known if this is true for other species.

As practical as they are, antlers are short-lived and grow again from scratch every spring. In winter, after a set of antlers has grown to full size and the mating season is complete, the velvet disappears and the animal sheds, or "casts," its antlers. It then takes a needed break from the work of consuming enough calories to support those heavy racks, which can weigh upwards of 20 or 30 pounds. Elk retain theirs through the winter as the antlers help this species compete with other animals for food; they shed them in spring.

Despite how many antlers are lost each year, it can be challenging to spot them on the ground. Calcium-seeking rodents and decomposition make quick work of the nutrient-rich objects, so it's usually easier to find antlers on a trophy-hunter's wall than on the forest floor.