* Some rhinos have two horns: The African black rhinoceros and the African white rhinoceros both have two horns.
* The size of horns varies: Even within the same species, the size and shape of horns can vary greatly.
* Horns are made of keratin: This is the same material that makes up our hair and nails.
So, while many rhinos have at least one horn, some have two, and the number and size of horns aren't a reliable way to identify a rhino species.