Weed creature

The weed creature was an intelligent, mobile form of parasitic seaweed that inhabited the North Sea near the coasts of England.



Biology
Weed creatures fed on natural gas and generated massive amounts of foam. The weed reproduced rapidly and possessed a nerve centre, the creatures producing a pulsing sound like a heartbeat. They possessed stingers which infected any human who touched them, allowing the weed to mentally control them and also gain intelligence from the human brain. Both the weed and infected humans could produce poisonous gas. When the Second Doctor tried to convince John Robson that the weed controlled his mind, he responded "the mind does not exist. It is tired. It is dead. It is obsolete. Only our new masters can offer us life. [...] The body does not exist. Soon we shall all be one." The creatures were vulnerable to oxygen and high-pitched sounds, forcing infected humans to whisper so as not to damage the weed. If the weed infection was killed, the humans would be returned to normal unharmed. (TV: Fury from the Deep)

History
The Seventh Doctor once described the weed creatures as "primeval", existing since the days of the dinosaurs in Loch Ness. (PROSE: Christmas on a Rational Planet) Ancient mariners supplied a drawing of the creature in the middle of the 18th century, which appeared in a book of legends and superstitions the Doctor owned. (TV: Fury from the Deep)

In the late 20th century, a weed creature was sucked up by an off-shore Euro Sea Gas rig in the North Sea, where it came in contact with maintenance workers and infected them, including Oak and Quill, two engineers at the refinery commanded by Robson, who was later infected himself. The creatures used them to commit various acts of sabotage around the refinery, and in the space of a few days, the weed took over the crews of the off-shore rigs as the base of its nerve centre. Additionally, the weed accidentally infected Maggie Harris instead of Frank Harris, and Van Lutyens when the creatures attacked him. The possessed Robson told the Doctor that "our new masters" needed him to help with "the conquest of the human planet." Realizing that sound affected it, the Doctor used a recording of Victoria Waterfield's screams to destroy the creatures and their nerve centre, releasing the infected humans. (TV: Fury from the Deep)

John Smith mentioned "intelligent seaweed" to Joan Redfern, which she found amusing. (PROSE: Human Nature)