Answer:
Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.
Face with a tree, skin like the sea. A great beast I am. Yet vermin frightens me.
When I'm born I fly. When I'm alive I lay. When I'm dead I run.
According to the music industry, you can count on a midnight train and the devil to turn up here.
I am round as a bowl, deep as a tub, but all the world's water couldn't fill me up.
People take me on walks and I run and have fun. What am I?