Easy 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 everybody. What am I?
This riddle makes it harder for you to find the answer of it by mentioning its producing process which sounds pretty long, and you think it is something bigger or you use only occasionally.
Even though it adds the fact that it is used by almost everybody and you understand that it might be something causal, a pencil lead is not the first thing that comes to your mind. Therefore, if you want to figure out the answer of this riddle here, you need to think simple.
The answer of this riddle is a pencil lead.