A rhinoceros is a massive, thick-skinned animal that looks like it walked straight out of prehistoric times. These plant-eating giants can weigh as much as a car and stand taller than most adult humans. Their most striking feature is the horn (or sometimes two horns) growing from their snout, made of the same material as your fingernails but packed so tightly it becomes incredibly hard and strong.

Rhinos live in Africa and Asia, spending their days grazing on grass and plants, wallowing in mud to stay cool, and generally minding their own business. Despite their enormous size and fearsome appearance, they're herbivores who prefer eating to fighting. However, they will charge if threatened, and few animals are brave enough to challenge a two-ton rhinoceros running at 30 miles per hour.

People often shorten rhinoceros to rhino, and the plural can be either rhinoceroses or simply rhinos.

Sadly, rhinos have become endangered because poachers hunt them illegally for their horns. Conservation efforts around the world work to protect these magnificent animals, because once a species like the rhinoceros disappears, it's gone forever. Some species that once roamed across continents now number only in the dozens.