Tallon IV is a planet found in the GameCube classic Metroid Prime. In the game, it is one of two planets, in the Tallon system, that can sustain life. Many years ago it was one of the "main" homes to the Chozo, though that time has long past, as currently the only inhabitants are unintelligent creatures. However, during the events in the game, the Space Pirates also were on the planet, investigating the new substance known as Phazon.
A long time ago (apparently over 150 millicycles ago. How long a millicycle is is unknown) a meteor struck the planet, though greatly vaporized upon impact. However, the meteor shed a load of a destructive and dangerous substance known as Phazon throughout the planet, which ultimately killed the Chozo despite all their efforts to stop the spreading radiation.