Keltan

Keltans are a sapient amphibious species of jellyfish-like creatures from the planet Orbis.

Sadly, they became extinct when their homeworld was destroyed by Morbius' stellar manipulator.

Biology
Keltans physically resemble large jellyfish with tentacles in place of legs. They change color according to their emotional state, for instance, becoming green when they feel fear. Unlike Earth cnidarians, Keltans are amphibious and need to spend part of their lives on land. According to the Doctor, Keltans have very short lifespans.

Culture and society
In the past, Keltans used to ritually cannibalize their dead and regurgitate their bodies to fertilize the ocean floor. The Doctor convinced them to abandon this practice.

Keltans are a friendly species, and welcoming towards strangers.

Appearances

 * Big Finish Eighth Doctor Adventures, Orbis (2009)