Today's cool animal sounds are the aggressive grunt, bellows, and squeaks of a male white rhino (Ceratotherium simum).
African rhinos are quite interesting creatures, with "horns" on their faces that are made up of the same keratin that's in your finger nails, and very unlike true horns. They have a good sense of smell and also hearing, but their vision is comparatively quite poor. They like to roll in mud, which acts as a sort of protection from bugs and the sun. Both African rhinos are endangered.
White rhinos are far more placid than the black rhinos, which are known for being quite aggressive. The two species look quite similar, and, despite what their names imply, really do not differ much in terms of color. They are both this sort of uniform gray. Other than behavior, one of the most noticeable differences between the white and black rhinos is the shape of their mouths. Black rhinos have a finger-like upper lip that is better for stripping leaves off of planets. White rhinos, on the other hand, have wide mouths that are almost like lawn mowers, and are quite efficient at taking in grasses. This wide mouth is one possible origin for the name "white," being caused by a mistranslation.
I have had the privileged of touching the skin of a black rhino at a zoo several years ago. Apparently, you can't really train a rhino for the usual husbandry behaviors as you would another animal. Usually, the keeper uses food rewards to get the animal to perform the behaviors so that important checks can be made on the animal's overall health. With a rhino, however, the form of praise they use is actually pats and rubs, which the animals truly seem to enjoy. I went to the zoo in question with a college class. Due to the fact that we were adults and thus very unlikely to do anything stupid, the keeper offered us the chance to pat one of these magnificent animals while she was training him to go into a transport carrier. The feel of the skin was like nothing else, and quite difficult to describe. The skin is rough, almost like concrete, and yet also yielding and slightly warm and fuzzy at the same time. It's an experience I will never forget.