Lens (do you see what i've done there....?!)

Lentils are shaped like a lens. In fact, lens is the latin word for lentil. The size and appearance of lentils varies depending on the variety.

According to the Bible, Esau was tricked into selling his birthright for a pottage of lentils. (Genesis 25:34)

Lentils have been found in Egyptian tombs that date from 2400 BC. It may have been used as an aphrodisiac. They also thought that the lentil enlightened the minds of children, making them more cheerful and studious.