Aurora Unit 313 is the theme that plays during the fight with the boss of the same name in Metroid Prime 3: Corruption. It is a remix of Darkness, Dark Samus' theme from Metroid Prime 2: Echoes, (Which was a remix of the Zebetite theme in Metroid: Zero Mission.). The theme is slow and ominous during the initial phase of the battle, but becomes faster and gains an alien-sounding melody when the Unit becomes airborne. In Metroid Prime Trilogy, the theme has been added to the Soundtrack Gallery along with the Berserker Lord Theme in place of the Bryyo Thorn Jungle and Metroid Battle Themes.