I have 3 riddles for you that I got from here.
Riddle 1: I am larger when cold and shrink when warm. You can see me, but you cannot touch me.
Riddle 2: When people need me, they throw me away. when I’m not needed they take me back.
Riddle 3: The more you give me, the richer you get. When you rob me, only you get poorer.