Fullerene molecule. Computer artwork of the spherical fullerene molecule C320. Fullerenes are a structural type (allotrope) of carbon. The molecular model here shows the spherical arrangement of the 320 carbon atoms in rings of hexagons and a few pentagons. The spherical fullerenes are sometimes referred to as buckyballs, after the first such molecule to be discovered (C60, buckminsterfullerene). As of 2006, research is being conducted into the use of fullerenes for medical purposes. Fullerenes are also being investigated for their physical and chemical properties.