What has a shell but isn’t a snail?

Riddle Explanation:
The riddle, “What has a shell but isn’t a snail?”, cleverly refers to a pistol. While snails have protective shells on their backs, a pistol uses shells—which refer to bullet casings that hold gunpowder and the projectile. This riddle plays on the different meanings of “shell,” highlighting how one word can describe both nature and firearms.