Answer:
Iron on a mammal. Mammal on your feet.
There are several different kinds, but the one you pick doesn't do its job. What is it?
He has married many women but has never married.
If I have it, I don't share it. If I share it, I don't have it. What is it?
By Moon or by Sun, I shall be found. Yet I am undone, if there's no light around
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?