Answer:
Two little holes in the side of a hill. Just as you come to the cherry-red mill.
Everyone has it and no one can lose it, what is it?
I dig out tiny caves and store gold and silver in them. I also build bridges of silver and make crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs my help. Yet many people are afraid to let me help them.
Runs smoother than any rhyme, loves to fall but cannot climb.
If a man carried my burden, he would break his back. I am not rich, but leave silver in my track.
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?