Answer:
What is it that given one, you’ll have either two or none?
Face with a tree, skin like the sea. A great beast I am. Yet vermin frightens me.
What is that which, though black itself, enlightens the world without burning?
You heart it speak, for it has a hard tongue. But it cannot breathe, for it has not a lung.
A tiny bead, like fragile glass, strung along a cord of grass.
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.