Answer:
I am always around you but often forgotten. I am pure and clean most of the time, but occasionally rotten. What am I?
I fill a room but take no space.
I work when I play and play when I work
I dig out tiny caves and store gold and silver in them. I also build bridges of silver and make crowns of gold. Sooner or later everybody needs my help yet many people are afraid to let me help them.
I am carried by mad animals.
What is always coming but never arrives?