It consists of aggregated hollow keratin fibers. Keratin is a substance similar to hair and fingernails but it lacks the outside cuticle. Rhinos use their horns for defense, as well as to dig, and to pull up small trees or push limbs. Rhinos are pachyderms, and do not sweat. A coating of mud offers a means of cooling the body.
Mud can take over an hour to dry and absorbs body heat in the process.
A thick coating of mud also offers protection from flies, ticks, and lice. Black rhino males are essentially solitary and have individual territories, but these are not strictly held. Territories often overlap, and several males often share a common water hole. Female black rhinos often share overlapping ranges but are solitary except during estrus and when they have young. Suckling calves travel with their mothers and sometimes with the previous offspring, if that offspring is female.