A fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are also called buckyballs, and cylindrical ones are called carbon nanotubes or buckytubes. Fullerenes are similar in structure to graphite, which is composed of stacked graphene sheets of linked hexagonal rings; but they may also contain pentagonal (or sometimes heptagonal) rings.
The first fullerene to be discovered, and the family's namesake, buckminsterfullerene (C60), was prepared in 1985 by R. Smalley, R. Curl, J. Heath, S. O'Brien, and H. Kroto at Rice University. The name was an homage to Buckminster Fuller, whose geodesic domes it resembles.