Solve the riddle:
In marble halls as white as milk,
lined with a skin as soft as silk.
Within a fountain crystal-clear.
A golden apple doth appear.
No doors there are to this stronghold,
yet thieves break in and steal the gold.
What is it?

Below you will find a hint and the correct answer to the riddle.
Little hint:
Show Hint
Hint: E**.
Right answer:
Show answer
Answer: Egg.