Both black and white rhinoceroses are actually gray. They are different not in color but in lip shape. The black rhino has a pointed upper lip, while its white relative has a squared lip. The difference in lip shape is related to the animals' diets. Black rhinos are browsers that get most of their sustenance from eating trees and bushes. They use their lips to pluck leaves and fruit from the branches. White rhinos graze on grasses, walking with their enormous heads and squared lips lowered to the ground. Black rhinos boast two horns, the foremost more prominent than the other. Rhino horns grow as much as three inches a year, and have been known to grow up to five feet long. Females use their horns to protect their young, while males use them to battle attackers. The prominent horn for which rhinos are so well known has also been their downfall. Many animals have been killed for the hard, hairlike growth, which is revered for medicinal uses in China, Taiwan, Hong Kong, and Singapore. The horn is also valued in North Africa and the Middle East as an ornamental dagger handle.