Energy unit Nestene energy units were hollow , plastic meteor ites utilised by the Consciousness to travel through space and as control units for the Auton s . 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 centimetres 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 " ) In another invasion , energy units fell to Earth in groups of 2 to 3 to over 200 . ( AUDIO : " Earthfall " ) Energy units contained portions of Nestene intelligence , which would be collected by Auton s . 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 " ) If an energy unit couldn ' t be retrieved , it could link up with a computer since Nestene energy existed as light , using computer wires defensively while the energy travelled to join the other units . ( AUDIO : " Bridgehead " ) Independently , an energy unit could be connected directly to an Auton to animate it , ( TV : " Terror of the Autons " ) or merely be in range of an Auton . ( GAME : " The Christmas Trap " ) Alternatively , a sphere could be linked up to a satellite where it could receive the signal . A unit could vaporise 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 unit could send a distress signal to a spearhead cluster to attempt realignment with the cluster to be rescued . A cluster 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 " ) In the 1980 s a Nestene sphere came to Earth to a village . The locals thought that it was a fallen star and built a plastic Christmas village around it . However , all people who came to visit the Christmas village vanished . The Eleventh Doctor heard about it . Together with Amy he came to investigate . When he found the sphere he used it to close portals , which increased its range , making areas safe when it passed through the portals and closed them . He put the sphere back into hibernation and transported it to Bakelite , an uninhabited planet . ( GAME : " The Christmas Trap " )