Saturnyne was an ocean planet far from Earth. It was populated by a race of advanced, sapient, and parasitic ichthyoids who swam through its vast ocean. It was destroyed by cracks in space and time generated by an exploding TARDIS. At least some of the creatures fled through one of the cracks into 18th century Venice, where they were planning to restart their society. However, only the male offspring, along with their Mother, survived the journey and their survival depended on the population being expanded. The planet of Saturnyne was forever lost to 'the Silence'. Little else is known about the environment and ecosystem of the now dead planet.
The planet may have been restored by the The Doctor.