Answer:
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.
This thing all things devours: Birds, beasts, trees, flowers; Gnaws iron, bites steel; Grinds hard stones to meal; Slays king, ruins town, And beats high mountains down.
It flies when it's on and floats coming off.
A kind of weather that comes your way, but add a "D" and it will run away
I am black when I am clean and white when I am dirty?
What covers its face with its hands, speaks no language, yet most known what it's saying?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?