Gravemind is a musical piece included in the second disk of the Halo 3 Original Soundtrack. It includes the tracks Gravemind, Fated Journey, Flee, and Familiar Ring.
The song is relatively quiet until around 1:01, when the music's tempo rises with intense, electrically-generated sounds. These sounds are from the Halo: Original Soundtrack piece Shadows, apart from the Gravemind speaking in the background, which may result in the name of this track. This is a classic Flood motif, meant to involve the player in the game with its fear-instilling beat and sounds. At approximately 1:52, the excerpt dies down and a chorus begins a slow melody. In the Floodgate gameplay, this would be when the Shadow of Intent arrives at the Battle of Voi, and also at the start of the cutscene where the Arbiter kills the Prophet of Truth. After this (at around 2:50), another chorus will begin a second Flood musical, which plays as the Prophet of Truth begins to be infected by the flood prior to his death. This beat is generally based on a group of singers, and has an eerie feeling to it. At about 3:12, a short violin solo plays numerous high-pitched notes extremely fast. Finally, the Halo 3 theme plays until the end, with the exception of a drum-solo in the middle of it.
- The background message often refers to a line deciphered as "Side by side we march as one. Humans and Elites will die. Earth will fall if we strike together. So forth shall all life."
- The name Familiar Ring fairly obviously refers to Installation 04B, the new Halo under construction over the Ark.