Answer:
You use it between your head and your toes, the more it works the thinner it grows.
Brown I am and much admired; many horses have I tried; tire a horse and worry a man; tell me this riddle if you can.
Face with a tree, skin like the sea. A great beast I am. Yet vermin frightens me.
What is it which builds things up? Lays mountains low? Dries up lakes, and makes things grow? Cares not a whim about your passing? And is like few other things, because it is everlasting?
A home of wood in a wooded place, but built not by hand. High above the earthen ground, it holds its pale blue gems. What is it?
This food is a tortilla filled with cheese and sometimes chicken before being heated or cooked.