Tritovore

The Tritovores were a species of fly-headed humanoids.

Biology
Tritovores were green-skinned humanoids with insectoid heads resembling those of flies. Their heads had two large compound eyes, and several complex parts making up a mouth. Tritovores communicated by clicking these mouth parts to produce sound. They had simple, three-digit hands. They ate the faeces of other species. (DW: Planet of the Dead)

Technology
The Tritovores had fairly large starships used for trade which are powered using a crystal nucleus, kept floating with four anti-gravity clamps. Ventilation shaft connected the various parts of the ship, which were kept shut with a series of forcefields. The ship also The ship were made of photavine steel, allowing the ships to become cooler when heating up on the outside.

Other technology included a ship-based communication system and a telepathic translator, allowing them to understand other languages. (DW: Planet of the Dead)

History
In 2010, a Tritovore ship came to San Helios, planning to trade with the inhabitants. They found that the whole planet had been cleansed of life by the Alien Stingrays. During their descent, the stingrays jammed the ships' ventilation system and caused the ship to lose velocity and crash. The only known survivors were Sorvin and Praygat.

When the 200 arrived on San Helios, the Tritovores believed that the bus was a weapon of some kind, possibly the reason why they crashed. They brought the Doctor and Christina de Souza to their ship, but the Doctor was able to convince them that were only there by accident. The Doctor planned to use the anti-gravity clamps from the Tritovore ship to move the 200, but when Christina was attempting to get it, her body heat woke up the stingrays trapped in the ship. They woke up and ate Sorvin and Praygat. (DW: Planet of the Dead)

Trivia

 * According to Russell T Davies, they will hopefully be remembered as well as the Daleks and the Cybermen.
 * Presumably, the Tritovores are named after detritovores, creatures like flies which feed on detritus.