Answer:
Although my cow is dead, I still beat her. What a racket she makes!
Who eats a lot of iron without getting sick?
No matter how little or how much you use me, you change me every month.
A circle of stones, never in rows. Stacked one on the other, mystery it sows. What is it?
What doesn't get any wetter, no matter how much rain falls on it?
You use it between your head and your toes, the more it works the thinner it grows.