Zolfa-Thuran

The Zolfa-Thurans were an intelligent cactus-like species who were the original inhabitants of the planet Zolfa-Thura. The last survivor of the race, Meglos, impersonated the Doctor in an attempt to steal a Zolfa-Thuran energy source called the Dodecahedron.

Physical characteristics
The Zolfa-Thurans are normally immobile, cactus-like plants. Reaching around 1.5 metres tall, the Zolfa-Thurans can't actually do much. They seem to have telepathic powers which allows them to be very perceptive and allows them to communicate with other life-forms.

Technology
The Zolfa-Thurans have access to very advanced technology. One of the more unusual devices turns the target into energy. While they are in the energy form, they can possess a humanoid and can then interact with their environment. They can also change the appearance of the possessed humanoid, but only to a similarly shaped being. As well, the host takes a more cactus-like appearance over time.

Another major technological development is the Dodecahedron. The Dodecahedron can produce enough energy to power the galaxy, or a galaxy-spanning weapon. The Dodecahedron was being used by the Tigellans to power their city.

History
Soon after the creation of the Dodecahedron, the Zolfa-Thurans went to war to stop the use of this enormous power-source. During this war, the entire planet was ravaged, leaving the only sand. Meglos, alone of the Zolfa-Thurans, survived the war and tried to get back the Dodecahedron. Though he succeeded in obtaining it, Zolfa-Thura and everyone on it was destroyed due to the Doctor's meddling.