Rutan Host

Rutans
Doctor Who alien
Type	Shape-changing protean lifeforms
Affiliated with	Rutan Host
Home planet	Ruta 3
First appearance	Horror of Fang Rock (1977)

Rutans are a fictional extraterrestrial race from the British science fiction television series Doctor Who. They have been at war with the Sontaran Empire for more than 50,000 years, (though another account claimed 10,000 years, though it is not known whether this Rutan was using a human timescale) and this war dominates both cultures to the exclusion of all else. The Rutans only appeared on television in the serial Horror of Fang Rock, in which a single Rutan is encountered, though they are mentioned in some serials featuring Sontarans (The Time Warrior, The Sontaran Experiment, The Two Doctors and "The Poison Sky", as well as The Last Sontaran and Enemy of the Bane episodes of Doctor Who spin off The Sarah Jane Adventures).

In their natural forms, Rutans resemble large green jellyfish, glowing blobs of biomatter with long ropy tentacles. They are amphibious and can cling to sheer vertical surfaces, with considerable mobility out of the water despite their shape. Rutans can also generate lethal bioelectrical shocks, and seem to be able to absorb electrical energy directly for sustenance. They reproduce by a process similar to binary fission. Rutans can speak, although the exact mechanism by which this works is unknown as no mouth has been observed on their body. The Rutan observed in Horror of Fang Rock spoke with a harsh, tinny male voice, and also used the pronouns "we" and "us" when referring to itself, suggesting that the species may exist as a kind of hive mind.

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Wikipedia