I am an egg that contains a palace, or rather, I am a palace that has been contained in an egg.
I am a marvel made into a miniature so that I can travel between worlds.
If you were to discover me in the underworld and take me to the upper world, you would find that I am a palace you can enter. You may take from me what will best serve.
That is all I can say. To say anything more would be to give my secrets away.