When Bilbo first meets Gollum in the cave in The Hobbit: An Unexpected Journey. He asks Gollum to lead him out of the cave, but Gollum refuses unless they play a game of riddles.
The Box Of Gold
One of the riddles Bilbo tells Gollum is that there is a box with gold inside, but there is no lock, no key, no hinge or lid.
Gullum manages to answer the riddle correctly.
What was the answer to the riddle?