What we didn't know is that each of these kingdoms has a king. Well, the little kingdoms are more like principalities, but who cares?
More fun puzzle clues:
The animal king isn't actually a lion - it's a cockroach.
The court of the dinoflagellate king is ornate and filled with intrigue. But very tiny.
The mineral king is a prehistoric radioactive meteor in the middle of a glacier in Alaska.
The plant kingdom actually is a misnomer - it has a queen.