Coloured scanning electron micrograph (SEM) of carbon nanotubes grown on a silica disc surface. Carbon nanotubes are rolled sheets of carbon atoms that form cylinders. They are structurally related to fullerenes - cages of carbon atoms discovered in 1985. The cylindrical carbon nanotubes can be either single-walled (SWNTs, curly) or multi-walled (MWNTs, straight). MWNTs have multiple carbon wall layers which do not change the nanotubes mechanical or electrical properties. Nanotubes are grown by several laboratory techniques and they are just a few nanometres in diameter and several microns long. Nanotubes have a very broad range of electronic, thermal, and structural properties that change depending on the different physical parameters of nanotubes. SWNTs and (MWNTs) can be formed to produce nanofibers and nanoelectronic components. Magnification: x100, 000 when shortest axis printed at 25 millimetres.