Chozo Ruins is a theme in Metroid Prime, playing in the area of the same name. The song was meant to be a build up for the song heard in the Tallon Overworld after the Spider Ball was received, which coincidentally shares the same drums, beat and tempo. The drum beat in the Chozo Ruins theme does not begin until the Morph Ball is regained. Additionally, near the end of it, a melody nearly identical to the latter part of the Metroid Prime Theme is heard. The Ancient Chozo Ruins theme plays when first entering the Ruins, and in later portions of them close to the Hall of the Elders.
The theme can be heard here: .