Scandium is a rare earth element mostly used in alloys of aluminum. It’s depiction as polar bear is pretty much a pun with a little bit of the fact that polar bears are getting rarer.
Wombats are the Titanium of the marsupials. They are tough heavy and very strong. Wombats are somewhat rodent like eating roots, grasses and have similar teeth to rodants. In Australia they are can be involved in road accidents, often causeing significant damage to vehicles involved. They are a covergant evolutionary species. Titanium is very like them in being a adaptable, strong and hard metal.