Saturnyne

Saturnyne was the home of the Saturnyns. According to Rosanna Calvierri, Earth had an ocean like that of Saturnyne.

The planet knew about and had considerable technology, including weather control and perception filters. The residents also knew about Gallifrey and the events of the Last Great Time War.

At some point in the planet's history, it fell to a mysterious crack in space and time that consumed its skies. The planet was lost to what Rosanna referred to as "silence". A large number of Saturnyns escaped the planet through the crack to 16th century Venice. They planned to turn the city into the new Saturnyne but were thwarted by the Eleventh Doctor. (TV: The Vampires of Venice)

Behind the scenes
According to The Monster Vault, Saturnyne was a forgotten casualty of the Last Great Time War, writing that the former water world was hit by a shockwave of the War's temporal disruption; the world went from a planet filled with sealife to one where its inhabitants evolved without natural laws of evolution, becoming strange looking beings that could move from the darkest depths of the seas and onto dry land. Upon looking at their new forms, the unnatural creatures cursed those who were responsible for their new, semi humanoid forms.