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- This article is about the theme of Mother Brain's final form. For her original theme, see Zebetite (theme).
This theme begins playing after Mother Brain is seemingly defeated in the same manner as the first game, only to rise up and reveal her full form. The theme continues playing throughout the Final Conflict, including the scene where the Big Metroid temporarily incapacitates Mother Brain and transfers her energy to Samus Aran. Once the Big Metroid is killed by Mother Brain, this theme stops playing, and Crateria Surface plays for the remainder of the battle.
Mother Brain features an unusual time signature and rhythm, forcing listeners out of their comfort zone. The harmony is constant throughout the song as a relentless constant bass line with a rising chromatic chord progression, reminiscent of the Zebetite theme from the first game, with each note accompanied by a heavy drumbeat. The melody is a harsh and piercing series of dissonant organ chords, frequently followed by a falling glissando. The result is a theme intended to invoke a sense of terror and hopelessness.
In 2011, the theme was performed by live orchestra as part of the Metroid arrangement in PLAY! A Video Game Symphony. In 2013, the theme was arranged by the WDR Radio Orchestra as part of Into Red, Into Dark, heard twice during the medley.
The original theme can be heard here.
- Since the release of Super Metroid, many other boss themes have borrowed elements from the Mother Brain theme, particularly the concept of harsh dissonant organ chords that rise and fall in pitch. For example, this can be heard in Parasite Queen and Boss Queen.