The buckyball was first discovered 25 years ago by a group of scientists at Sussex University in the south of England and Rice University, in Texas, and named after the architect Richard Buckminster Fuller, noted for popularising the geodesic dome.

To mark the discovery of this specially shaped molecule composed entirely of carbon on 4 September 1985, Google has changed the second O in its logo to a manipulatable version of a buckyball for the day.

Buckyball is the colloquial name used to describe a spherical fullerene – an abbreviation of the Buckminsterfullerene C60, its full name. For their discovery of fullerenes, Sir Harold Kroto of Sussex and Richard Smalley and Robert Curl of Rice were awarded the Nobel prize for chemistry in 1996.

There are a variety of different buckyballs depending on the structure – the most recognisable, and first discovered, being the Buckminsterfullerene C60. It shares the geodesic structure of a panelled football and is the smallest fullerene molecule in which no two pentagons share an edge – giving it structural strength [see footnote].

The C60 is found in soot, though rarely occurs in nature. Other allotropes of carbon include diamond and graphite but the discovery of fullerenes greatly expanded this.

The unusual spherical arrangement of the molecule led to the nickname buckyball. Scientists have since discovered buckytubes, nanotubes, megatubes and nano onions.

The unique chemistry of the family of particles has been widely researched for use in electronics, nanotechnology and many other fields of science.

Google has previously used its logo to mark other anniversaries and events. Earlier this year it marked 30 years of Pac-Man by converting its name into a playable version of the game.

• This article was amended on 7 September 2010. The original omitted to credit Sir Harold Kroto of Sussex University for his joint discovery of the C60. Regarding the above article's assertion that the C60 "is the smallest fullerene molecule in which no two pentagons share an edge", a reader says: "The smallest sphere whereby the pentagon edges do not touch each other is an icosa-dodecahedron, twelve pentagons surrounded by triangles."