Shakara

Shakara was a planet which was home to aquatic beings including the Valky clan and an enemy with whom they were at war. The Valky clan bred the Zaralok, giant armoured sharks, as a weapon to win the war but the Zaralok turned on their creators, eating the Valky clan as well as their enemies.

A Zaralok was transported to 23rd century Earth via a temporal rift, where it attacked the aquatic research station Poseidon 8 until it was sent back to Shakara by the Eleventh Doctor and Amy Pond. (VG: Shadows of the Vashta Nerada)

Behind the scenes

• While Shakara is never mentioned in Shadows of the Vashta Nerada's character dialogue, the planet and its role as the origin of the Zaralok is described in a "Who Fact" popup initiated by examining the first porthole on the USS Eldridge.