Generate an interesting riddle and give the answer.
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 (graphite)
Complete the following task based on the instruction and optional input provided.### Instruction:
Generate an interesting riddle and give the answer.

### Output:
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 (graphite)