In my world metal is difficult for humans to obtain, it cannot be found mining, at least not in any useful form.
Instead, to obtain metal, you have to slay large and very dangerous creatures covered in metal scales. The metal scales make for great armor thus the creatures are very difficult to slay.
The metal creatures range in size from roughly a cow to an elephant.
The metal creatures need to obtain their metal in such a way that a human cannot just obtain metal in the same way, thus circumventing having to slay the metal creatures.
Is it possible for the creatures to have metal scales?
I would appreciate examples from nature of naturally occurring metals in animals, if there are any.
If it is relevant to the question:
The society is feudal with the nobility owning almost all of the metal, it is illegal for someone who is not noble to own metal. Most tools are stone age but with better craftsmanship.
When referring to metals I mean the metals that are traditionally used to forge tools and weapons, such as iron, copper, tin etc