Tak the Great Juju Challenge. They are purple females that have a baby Rhino hidden somewhere. Rhinos are very common, and can be found in Silver Stone Coast (they're first encountered here), Gates of Nocturne, and much more places. Rhinos are found sleeping, so you must find their hidden baby to wake them up (although Lok's Stink spell can wake them up without the baby rhino). Rhinos can be ridden to defeat enemies, break walls and vines, and enter secret or blocked pathways. Unlike Mammoths, Rhinos do not attack if you attack them. However, if they spot you with their baby, they'll chase you and eventually ram into you which causes you to fly in the air. By touching a Rhino's horn causes you to instantly flinch. To get on a Rhino, just press the Jump button. You, of course, cannot ride the baby Rhinos.