Answer:
What is the thing which, once poured out, cannot be gathered again?
What can run but can’t walk?
By Moon or by Sun, I shall be found. Yet I am undone, if there's no light around.
What gets wet while drying?
What loses its head in the morning and gets it back at night?
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?