The Nestene was a being of pure psychic energy, somewhat cephalopod-like in appearance.The Nestene had the ability to possess plastic, shunting some of its consciousness into the plastic and allowing it to control it. Over the course of its invasions it possessed the Autons, inflatable chairs, dolls, telephone cords, plastic daffodils, and garbage bins. The Nestene could transport sections of its mind through radio waves. It could also create a body out of the plastic for itself, allowing it to manipulate its surroundings.
The body created by the Nestene out of plastic was generally similar to its real appearance being somewhat like a giant octopus. After the stresses of the Last Great Time War, it manifested as a more liquid form, which had a humanoid face.
The Nestene Consciousness is a telepathic gestalt entity. It travels through space in hollow spheres known as energy units. These units make planetfall in formation, appearing like normal meteorites to indigenous lifeforms. Once the consiousness within those spheres is recombined and placed in an environment tank the Nestene will take on a form that it believes to be perfectly adapted to the planet on which it has landed. The key part of a group of energy spheres is the Swarm Leader, which is able to create a facsimile of a native, or create an original native-form from scratch.
On some worlds its takeover strategy is as follows: The first spheres to arrive will attempt to place a local being under some form of mental control. It will then take over a plastics company and fashion plastic automatons known as Autons. These Autons may include replicas of key authority figures as well as simpler automatons. The Nestene will then use the Autons as an army to conquer the planet. Autons are controlled on the astral plane, and sub-etheric beams can disrupt this telepathic control. In some cases, the Nestene requires a relay station or transmitter to control Autons. This only seems to be necessary to control large numbers at once
At the beginning of the universe, Shub-Niggurath came into this universe from the previous universe pregnant. She was able to deliver her child on Polymos, who infused into the entire planet. This Nestene Consciousness created Swarm Leaders, which it sent out to other planets.
The Nestene had been invading planets for billions of years, which they use for sources of plastic and protein. They first send several plastic meteors to the planet. These asteroids could telepathically control specially created plastics, but are more effective when combined together. The Nestene would then control people to create Auton forces to help with the next waves of invaders. Some of the planets which the Nestene Consciousness took over includes Cramodar and Plovak 6.
The Nestene's first attempted to invade the Earth in the 20th century, using human-looking Autons to replace key government figures, was thwarted by UNIT with the help of the Doctor.
In their next attempt, the Master obtained one of the Nestene meteors and took over a plastic company. Using the plastic company to create fake daffodils, disguised Autons would hand out these flowers for free. Eventually, once millions had been distributed, the Nestene would activate them by remote radio signals, causing them to suffocate and kill millions of people. The Master also created dolls, inflatable chairs and telephone chords to kill difficult individuals. The Doctor was able to figure out this plan and convinced the Master that the Nestenes were too dangerous to be reliable allies, and they reversed the radio beam the invasion force was coming in on, sending it back into space.
The Doctor helped UNIT to defeat another Nestene invasion. This did not appear to tax him overly, as he found time to take dance lessons during a lull in the crisis.
In 1989, the Nestene Consciousness tried to take over Earth using the computer company SenéNet. The Doctor, Mel and The Brigadier prevented the Consciousness from taking over the Earth. At the same time, it established a front operation called Galaxy Plastics Inc., and was still operational and undiscovered in August 1990.
In the late 1990s, staff in a UNIT warehouse accidentally reactivated an Auton from the Nestene's first invasion attempt. This started a series of events leading to a new Nestene invasion that was stopped the the cybernetically enhanced UNIT agent Lockwood and his team.
In 2005, the Nestenes infiltrated Earth once more, using warp shunt technology. The Nestenes had lost their food planets in the Last Great Time War, so their intent was to overthrow and destroy the Human race, as Earth was ideal for their consumption needs, being filled with smoke, oil and various pollutants. The Doctor eventually defeated them by spilling a vial of anti-plastic solution into the vat of molten plastic which housed the main bulk of the Consciousness, causing it to explode.
In the 101st century, the Nestene Consciousness was attempting to completely leave Polymos after an invasion of the Time Lords. It chose the New Earth Republic and attempted to transport its entire body to Reef Station One with the help of Walter J. Matheson. It was stopped by the Doctor, who trapped it in the body of an advanced Auton.