Answer:
I grow up while growing down
I am the beginning of eternity the end of time and space the beginning of every end the end of every place.
I am pinched by grandmas
What goes through cities and fields but never moves?
Brown I am and much admired; many horses have I tried; tire a horse and worry a man; tell me this riddle if you can.
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.