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.

Magic Egg in The Norka, Russian Fairy Tales Collected by W.R.S. Ralston. Egg by Faberge.