If Bitcoin was a physical object, it would have the ability to change elemental form.
Meaning, Bitcoin would today be roughly "bronze", and in six months will be "silver", and a year later Bitcoin will be "gold", and another year later a BTC will be a flawless, 3 lb diamond.
Another good metaphor for Bitcoin - Dragons. They start small, but quickly grow beyond control...
https://www.youtube.com/watch?v=r1iW5o-l85w