Answer:
found at the back of the book.
I've got a beautiful beautiful hall all walled in red velvet with all white armchairs made of bone and in the middle a woman dances.
I am heavy forward but backward I'm not.
I run up and down the stairs without moving
I am always around you but often forgotten. I am pure and clean most time but occasionally rotten.
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.