A Nanoform. (TV: Prisoner of the Judoon)
Nanotechnology is the manipulation of matter on an atomic and molecular scale. They usually took the form of microscopic robots. Many species had developed nanotechnology.
The Tzun created nanites which could separate the DNA of a living hybrid organism. (PROSE: First Frontier)
The Chula created nanogenes to heal their soldiers during wartime. (TV: The Empty Child/The Doctor Dances)
The people of Avalon created nanotech which was mistaken for magic by human colonists. (PROSE: The Sorcerer's Apprentice)
The Farrians used teleport disks that incorporated nanotechnology. (AUDIO: The Invasion of E-Space)
In 2009, Genetec Systems created nanoforms. Androvax planned to use them to build a spaceship and then destroy Earth, but was defeated by Sarah Jane Smith and her gang. (TV: Prisoner of the Judoon)
Selachians created nanites which could repair their battlesuits. (PROSE: The Final Sanction)
In 24th century Prague, nanoprobes were used to create everything from cars to houses. (PROSE: Nanomorphosis)
The Travellers used nanotech in some of their bonding ceremonies. (PROSE: Happy Endings)
The Daleks created the Contagium, which could infect biological hosts with nanites, allowing the Daleks to control their minds. (COMIC: Fire and Brimstone) They later created nanoclouds which converted humans into Dalek puppets. (TV: Asylum of the Daleks)
In 200,000 nano-termites were used as part of the Vomit-O-Matic. (TV: The Long Game)
The natives of Bellania II created nanotech which survived the collapse of their civilisation and the destruction of all life on the planet. (PROSE: Beltempest)
The quantum transducer used nanotechnology. (TV: Ghost Machine)