Answer:
I regularly change shape yet remain a sphere. I am always there but not often seen. What am I?
I am the kind of ant that's good at math.
What can be heard in court or used to carry briefs?
Drop me and the world will shatter. You can always find me where you empty your bladder. What am I?
What can you catch but not throw?
No matter how little or how much you use me, you change me every month.