A potato, a needle, a picture, a cyclone and a tornado are all potential answers to the riddle, "What has eyes but cannot see?" Each of these items has an eye, but none of them are capable of sight.
Riddles are some of the first brain exercises. They can be used as a memory prompt. By making a game out of an answer, the riddle assists the brain with recall. Another use for riddles is to pass on old sayings or bits of wisdom. This comes from the era when humans relied on oral communication to pass on knowledge. By challenging the listener to actively participate in the conversation, the riddle enhances the learning experience.