For starters, mammals have hair and nurse their young. Most mammals birth live babies, but not all. Monotremes are a type of mammal that lay eggs. A duck-billed playpus comes to mind:
Marsupials are also mammals, but they have a pouch for their babies to safely nurse as they continue to develop. Kangaroos fall into this category and so do
Webkinz koala bears.
Australia has the monopoly on these unique mammals. So now add this island continent to the places my safari-loving K wants to visit...after petting the leopards in Botswana (really...she wants to live there thanks to National Geographic).