A pool that Legarans live in
The Legaran species, hailing from the planet of Legara IV, is a mysterious alien species. After 93 years of preliminaries by Vulcan Ambassador Sarek, they finally made First Contact with the Federation in 2366, during the Legaran Conference.
The Legarans are strictly adherent to protocol. Though nondescript physically, they prefer to live in a pool of thick swirling ooze, which is carefully maintained at a constant 150 °C. The Legarans prefer no furniture and no (wall) decoration. (TNG: "Sarek")