Stingray

Alien Stingrays were creatures that lived in swarms of billions and due to there sheer mass were able to open Wormholes in space by moving at fast speeds.. They where named Alien Stingrays by UNIT as that they resembled Stingrays that live in Earths Sea.

Biology
The Stingrays had an exoskeleton of metal to enable them safe travel through the Wormholes they created. There digestive system allowed them to eat anything encluding metal which was used to make there exoskeleton once digested. They were seemingly unintelligent and incapable ofspeech. They acted on the instinct to devour and move on. They moved from planet to planet by opening wormholes. They created these by swarming around the planet many times so there sheer mass would rip time creating a wormhole they then travelled through.

History
A swarm of Alien Stingrays opened a wormhole that led them to the planet San Helios. There they swarmed the planet and devoured everything turing it into a barren desert. They then began making a second wormhole with which to leave the planet. A number of the stingrays were trapped in the hull of the Tritivore's ship. They were dormant there but a tempreture rise due to body heat awoke them and they devoured the two Tritivore occupants of the ship. Malcolm Taylor managed to close of their latest wormhole that lead to Earth. They merely made another one but the Doctor decided to guide this and all their future wormholes onto uninhabited planets were they could feed on natural structures.