The Sheliak were a non-humanoid R3-type lifeform whose homeworld is located in the Shelia star system.
Unlike most humanoids, the Sheliak preferred to exist in an environment that was the same temperature as their bodies (TNG episode: "Starship Mine"). They were also a xenophobic people, known for avoiding contact with the United Federation of Planets whenever possible. This may have been due to the Sheliak attitude that humanoids are an inferior form of life (often pejoratively describing them as creatures). (TNG episode: "The Ensigns of Command")