Carbon nanotubes are a type of carbon that has a cylindrical shape. They are made in such a way that the length: volume is 1.32 × 10 ৬: 1 which is more than any other substance. Although carbon nanotubes were introduced in the 1990's, Fullerin C60 was discovered in 1986 as the third form of carbon. Fullarin is also a nanotube. Fullerin's three discoverers ( Sir Harold Kroto, Rob Art F. Curil, Jr. Richard E. Smally) were awarded the 1998 Nobel Prize in Chemistry. Inside , a hallow structure made up of an atom-dense carbon sheet is called graphene. Carbon nanotubes can be single-walled or multi-walled , with open or closed mouths. Known as the smallest test tube in the world, the test tube is a carbon or nanotube which is listed in the Guinness Book of World Records . One end of which is bound by a fullerine cap and the size of the tube is 10 -24 dm 3. The longest carbon nanotube was made in 2009 with a length of 16.5 cm. The diameter of the thinnest carbon nanotube is 3 Å (Å = 1 × 10 -8 cm or 10 -10 m). The value of graphite is 3.4.