Karaten was a planet. It was home to a liquid life-form.
Having been hired by the Zaan to steal Honey Vox's Treed Crystal, Jebelex the Pulthasian hid on Karaten. Following his DNA trail, the Tenth Doctor and Martha headed to the planet but discovered that Jebelex had been eaten by a native liquid creature. The Doctor used a matter transmuter to freeze the creature before shattering it and retrieving the crystal. Before long the Vaan showed up and took Martha as his prisoner telling the Doctor to bring the crystal to the Vaan Homeword if he wished to save his companion. (COMIC: Lock, Stocks and Barrel)