Temple Key

From Wikitroid, the Metroid wiki

Temple Keys are items that appear in Metroid Prime 2: Echoes. They allow Samus to access the Dark Temples scattered throughout Dark Aether - ones in Dark Agon, Dark Torvus, the Ing Hive and the Sky Temple. Dark Torvus, Dark Agon, and the Ing Hive each need three keys to open, the Sky Temple needs nine. Most keys can only be retrieved with a certain ability. One Sky Temple key was recovered by a Luminoth thats body is at the Sky Temple gateway.