The Remoraxian Prime was, according to Brigadier Lethbridge-Stewart, "some sort of mother creature" to the Remoraxians. In 1974, it led the Remoraxians in their plot to flood the Earth and turn it into a waterworld, commanding them from a UNIT seabase off the coast of Great Britain.
When the Third Doctor confronted and threatened the Remoraxian Prime, it had the Doctor and the Brigadier sent to the bottom of the sea. Sarah Jane Smith and Liz Shaw rescued them. When it heard the Americans were planning to bomb Great Britain with nuclear weapons to stop the Remoraxians' flooding, it conceded it was "outmanoeuvred", and left the Earth, hoping meet the Doctor again. The bombing was subsequently called off. (COMIC: In With the Tide)