Answer:
I break down buildings, I crumble mountains but you can't see me. What am I?
I am round. I have only one line. Circle is not my name indeed. What am I?
I am not a toy though many use me for pleasure. I have a butt but I cannot poo.
Although a human shape I wear, mother I never had. By every miss I'm valued much, still my cruel fate is such by boys I am often despised. What am I?
Drop me and the world will shatter. You can always find me where you empty your bladder.
Two brothers we are, great burdens we bear. All day we are bitterly pressed. Yet this I will say, we are full all the day, and empty when go to rest.