Five Underground Kingdoms based on the Chinese classical elements.

So, in my story, the characters visit five(or four, I'm not quite sure what it should be currently) serperate kingdoms, and I thought it might be interesting if they were themed around the five classical Chinese elements. They don't have to be themed around them for the story to work, of course, I just thought it might be an interesting detail.

So, one of them is ruled by a Dwarf King, another is ruled by a Mushroom Princess, and yet another is ruled by a Worm Queen. The kingdom's population all consist of the ruler's respective species.

Any ideas for the other two kingdoms?

I was considering rock creatures for one of them