Answer:
What is it which builds things up? Lays mountains low? Dries up lakes, and makes things grow? Cares not a whim about your passing? And is like few other things, because it is everlasting?
What is neither inside the house nor outside the house but a necessity for any home?
Iron on a mammal. Mammal on your feet.
Fatherless and motherless. Born without sin, roared when it came into the world. And never spoke again.
You throw me out when you want to use me and you take me in when you don't want to use me. Who am I?
Disgusting creatures that would survive a nuclear strike.