The Wwafida were a plesiosaur-like species who lived on the planet Akkalla, and were presumed to be extinct. It turns out, however, that the Wwafida were not a separate species, but actually Akkallans who have progressed to a second and final stage of their life cycle. This stage was done by glands that were removed from the general populace when each of them turns 18 years old. This is true of the rebel leader as well, but thanks to a synthetic version of the glandular secretion created by Dr. McCoy, is able to undergo the metamorphosis into a Wwafida. He is then able to meet others of his kind who have retreated into the deep sea to avoid contact with their own descendants and bring them to the USS Enterprise. Once the Wwafida return, the leader of the oppressive Akkallan government resigns. (TOS novel: Deep Domain)