Answer:
What is common to eat before it's born and after it's dead?
It can be white or blue or black, Humped or have a horn. And when it talks it sings its menuets, as it's travelling the depths.
When it was young, it had a tail. When it grew up, it had knees
He's big, old and fluffy, And looking rather scruffy. He always needs a shave. It's best to just avoid him, And leave him in his cave
A pony trots his way through the world on these.
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.