The conversation between human and AI assistant.
[|Human|] Make up a riddle and give me an answer to the riddle.
[|AI|] Riddle: I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost everyone. What am I?

Answer: Pencil Lead.
[|Human|] 
Make up a riddle and give me an answer to the riddle.