Answer:
Covered in stone and sun. It's home to many but also none. What is it?
What can be swallowed, but can swallow you?
No matter how little or how much you use me, you change me every month.
Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.
What force and strength cannot get through. I, with a gentle touch, can do. Many in the street would stand. Were I not a friend at hand.
What is always coming but never arrives?