Answer:
A precious fluid, thicker than water.
You need a key to receive an answer from me. The answer you'll find is straight from your mind. What is it?
A serpent swam in a silver urn, A golden bird did in its mouth abide, The serpent drank the water, this in turn, Killed the serpent. Then the gold bird died.
What looks back but cannot see?
A tree with 5 branches, no leaves and no fruits
I can only be played on a windy day