From Creatures Wikia
Wyst (Cluelesseus officiusous)aquamite) - practically everything eats it, even creatures! Due to this it is often driven to extinction by over-predation in the early game, adding to the intensive micromanagement of its terrarium.
At the beginning of the game, a number of Wysts are spread throughout the marine terrarium. If it manages to live to its full age and die peacefully, it leaves a number of vivid blue eggs.