Answer:
I've been around for millions of years, but I am no more than a month old. What am I?
I open to close but I close to open. I'm surrounded by water but I'm never soaking. What am I?
People need me, yet they give me away every day. What am I?
As a stone inside a tree, I’ll help your words outlive thee. But if you push me as I stand, the more I move the less I am.
I begin and have no end. Eventually, I will be the ending of all that has begun. What am I?
No matter how little or how much you use me, you change me every month.