Energy unit
Nestene energy units were hollow, plastic meteorites utilised by the Consciousness to travel through space via warp shunt technology. (TV: Rose) The Tenth Doctor compared them to seeds. (PROSE: Autonomy)
Each unit was a translucent polyhedron, roughly spherical but made up of flat triangular sides; they were 8.5 inches in diameter, with a volume of 3,000 cubic centimeters and ranging in colour from pink to blue to purplish-green. They moved through space in swarm formations called "clusters" and landed on worlds through a thin funnel of superheated air about twenty miles in diameter; the first wave was composed of a spearhead of five or six units, followed by another fifty or so six months later. (TV: Spearhead from Space, PROSE: Autonomy)
Energy units contained portions of Nestene intelligence, which would be collected by Autons. If they were difficult to locate, they could increase their pulsation signals as the units were alive and part of the Consciousness. One energy unit was the "Swarm Leader," which was vital to creating a Nestene creature: once all units were collected, their contained intelligences were deposited into an environment tank to allow them to manufacture a body out of plastic which would serve as the central brain of the Autons. (TV: Spearhead from Space)
Independently, an energy unit could be connected directly to an Auton to animate it if there was no Nestene signal, (TV: Terror of the Autons) or could be linked up to a satellite, where it could receive the signal. A unit could vaporize itself, releasing energy and destroying the nervous system of any creature caught in it. They could shift into a liquid form, merging with other units and collecting energy, and this form would also allow them to kill directly. (HOMEVID: Auton)
A swarm in space could bounce their signals off of a Nestene creature and tune into the plastic-based environments of a planet. If the Nestenes' manifestation was destroyed, the units would crumple into themselves and lose their direction. (PROSE: Autonomy)