Careshi

The Careshi were the inhabitants of the planet Caresh. They were a humanoid, amphibious species with an advanced society. Careshi began their lives on land, and as they aged would eventually develop gills which allowed them to live in the planet's oceans.

The Careshi faced the threat of extinction when a passing neutron star threatened to disrupt their planet's orbit, making it uninhabitable. Roche tried to change the neutron star's path to put Caresh into a closer orbit to Beacon, its warmest sun, but with the Third Doctor's help he instead moved Caresh into a closer, more stable orbit around its cooler sun Ember, saving the Careshi in the process. (PROSE: The Suns of Caresh)