The Morg and Eymorg are the same race of the planet Sigmus Dricomus 7 splitted in two parts. This planet is a frozen world and host the males creatures (the Eymorg) on the artic surface. The women live underground in a climate-controlled cave. The cave is controlled by the "Teacher" and the Morg controls the Eymorg with a "giver of pain and delight".
Referring episode : Spock's Brain