The oldest examples of Jōmon pottery have flat bottoms, though pointed bottoms (meant to be held in small pits in the earth, like an amphora) became common later. In the Middle Jōmon period (3000-2000 BCE), simple decorations made with cord or through scratching gave way to highly elaborate designs. So-called flame vessels, along with the closely related crown-formed vessels, are among the most distinctive forms from this period; representative forms such as clay figurines of people and animals also appeared around this time. These figurines, called "dogū", are often described as "goggle-eyed", and feature elaborate geometrical designs, and short, stubby limbs. Scholars speculate they had religious significance and were used in fertility and healing rituals.