Answer:
The part of the bird, that is not in the sky, Which can swim in the ocean and always stay dry. What is it?
It is in every mountain, it's not in any hill, it's not in all the world, and yet it's in the mill.
What has only two words, but thousands of letters?
You can break it or drink water from it.
They come in many varieties: Red, Black, Dead, and Caspian to name a few.
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.