Tythonians are a sapient species of large blob-like creatures native to the planet Tythonus, which aren't naturally able to speak and need special communicator devices to communicate with other races.
Despite their beastly appearance, they are relatively peaceful beings which feed on chlorophyll (a molecule found in plant life) and mineral salts, and are well able to survive for years without solid food. They have very long lives, up to forty thousand years.
Their bodies are concealed in membranous skin and often form pseudopod-like structures. They also have a faint green bioluminescence and are able to weave a peculiar material, part mineral part organic, which they use to construct their ships and most of their technology.
They appear to be a highly advanced race, as they have the power to alter the curse of neutron stars, which they can direct against enemies who commit acts of war against the Tythonians. Since their population has grown to huge numbers, their planet is scarce in vegetable resources, but extremely rich in metal, which they are willing to trade with other species in exchange for food.
- Doctor Who season 17 - Creature from the Pit (1979)