The rhinocerous rolls around in the mud for various reasons: 1. To cool off, 2. To apply sun screen and 3. to keep the bugs from biting their skin. This gives his skin a rough coarse feel. However, if you feel between the folds, you will find the skin is actually soft to the touch.
The rhinocerous shapes his horn by rubbing it against trees, the ground, rocks or anything else available. This produces the standard curved shape. However, Yebonga, the femail rhinocerous shown in the picture, lets her horn grow straight. It keeps reaching a point where she can no longer eat off the ground because the horn gets in the way. The zoo keepers therefore have to trim the horn which is similar to trimming a toenail - except a lot bigger (they use a hack saw).
The Rhinoceros liked her hind area scratched, so she would move until you were properly positioned to perform the task. Then she would turn around when she wanted the other side scratched.
