Answer:
Iron on a mammal. Mammal on your feet.
What can be heard and caught but never seen?
Lighter than what I am made of, More of me is hidden Than is seen.
Turn us on our backs and open up our stomachs you will be the wisest of men though at start a lummox.
I bind it and it walks. I loose it and it stops.
My days are numbered. What am I?