Horns grow on the Bovidae’s head. If you cut down a horn or if it gets torn out by accident, the horn won’t grow back.
What’s on the head of an elk is called antlers. Those fall off and grow back each year. The older the elk is, the bigger the antlers will grow. If they are broken during growth, the injury will close up but a bending out of shape will reproduce each year after that incident.
Elk velvet antlers grow fast. In spring, or even at the beginning of March for the older ones, antlers from the previous year fall off. If they were cut, what was left on their head (commonly called the buttons), will fall off and new antlers will grow. Actually, antlers are similar to baby teeth: they fall off when the new ones are growing under. However, antlers grow a lot faster than teeth. Breeders say that if you take 2 pictures of elk antlers at 24 hours of intervals for the same animal, you will easily see the difference in the size.
Scientists pointed out the similarities between antlers and placenta: they are both a living matter, full of proteins, minerals and other nutriments. Moreover, elk antlers and placenta can be taken out without damaging the animal and they can reproduce almost infinitely.