Slythers
Slythers were native creatures of Skaro. They were occasionally utilised by the Daleks.
Biology
Slythers looked like large, black, jellyfish-like creatures. Their skins were thick and made them immune to the Varge plant stings. They moved slowly and groaned.
Appearances
The Dalek Invasion of Earth (TV)
War of the Daleks (Prose)
Legacy of the Daleks (Prose)
The Only Good Dalek (Comic)
Masters of Earth (Audio)