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General overview


Large, with tentacles connecting the being to its surroundings


Variable depending on creation stage

Method of attack:



The Proto-Gravemind, also known as the Brain Form[1] or the Proto-Compound Intelligence,[2] is an advanced Flood form created from the biomass of the most intelligent living organisms available, with the ultimate goal of creating a fully-functional Gravemind.


Creation and physiology[edit]

The infected Minister of Etiology, reduced to a disembodied head, while being absorbed into a Proto-Gravemind.

Proto-Graveminds are created when the Flood has amassed sufficient bodies and minds to become sentient. In order to create a viable "mind", large numbers of Flood forms and corpses are merged into a globular mass, which uses the combined knowledge derived from each host. They are usually formed in order to handle advanced tasks, such as piloting a starship, in which case Flood forms will merge as many hosts as possible with that knowledge, such as former pilots and officers. Rather than completely destroying a victim's consciousness, as a normal Flood form generally does, it interrogates its victims slowly, allowing their nervous systems to feed it information. The form tortures the host's mind with a loud buzzing sound, thus erasing all thought. Only after the host is stripped of all knowledge is the host killed by the Proto-Gravemind, although it is sometimes possible for a host to die before the Flood form has a chance to assimilate all of its memories.[3]

A small proto-Gravemind.

Presumably due to their knowledge and high level of intelligence, San'Shyuum are sometimes used to form the core "mind" of a Proto-Gravemind, such as the Minister of Etiology aboard Infinite Succor.[4]

Proto-Graveminds often pilot complex vehicles that require trained pilots, such as space-borne vessels. While combat forms can easily, albeit clumsily, pilot smaller vehicles like Warthogs, Scorpions, Wraiths, and Ghosts, Proto-Graveminds are needed for larger vehicles such as a starship. Since the Proto-Gravemind is stationary, it is likely that it directs nearby combat forms to pilot the ships, similar to the way a fully-formed Gravemind will direct Flood forms to execute battle strategies or other complex tasks.

A mid-sized proto-Gravemind.

Unlike all other known Flood forms, Proto-Graveminds are immobile and passive in combat. They have never been observed to move on their own, even when combat forms are fighting nearby. In fact, even when John-117 punched through the side of the Proto-Gravemind present aboard the Truth and Reconciliation during the Battle of Installation 04, the Flood form did not react at all; it is likely that until the transformation into a true Gravemind is complete, Proto-Graveminds are nothing more than an amalgamation of inactive bodies. Proto-Graveminds have also never been observed to keep any of their hosts' weapons. They use some of their hosts' legs as a means to support themselves, and one can see some of the bodies of the most recently assimilated, embedded in the Proto-Gravemind's mass, albeit deformed.

A large proto-Gravemind, maturing into a Gravemind.

Proto-Graveminds are capable of jamming or distorting radio signals within a significant radius around them. The means by which they do this is unknown; however, it may be related to the unexplained telepathy the Flood use to communicate with one another. In one instance, a Proto-Gravemind was shown to be capable of both jamming a real transponder signal and replicating it from its own position to draw in nearby human forces.[5]

Further evolution[edit]

The Proto-Gravemind must grow incredibly in size to reach its next stage of evolution, known as a Gravemind, a near-omniscient Flood form made of thousands of host bodies infused with the knowledge of each host that was used to make the Gravemind.[6] Graveminds are created once a Proto-Gravemind reaches a certain "critical mass" and develops a centralized intelligence. This happens only on extremely rare occasions, usually because the Flood is seldom loose on a large enough scale to allow Proto-Graveminds to grow large enough to become a Gravemind. Only two Graveminds are known to have ever been created; however, they seem to have the same memories, since the Gravemind present during the Human-Covenant War possessed detailed knowledge concerning the Forerunner-Flood war and even described the actions of the previous Gravemind during that time period as if they were its own.


Early concept art of a proto-Gravemind.

Proto-Graveminds have been encountered several times, in varying stages of size and potency.

The first recorded Proto-Gravemind was discovered on the surface planet of the Forerunner shield world Etran Harborage during a massive Flood outbreak in 2531. Judging by its huge size and its connection to several Flood colonies, it is likely that this Proto-Gravemind was on the verge of becoming a Gravemind. This Proto-Gravemind was destroyed by UNSC forces led by Sergeant John Forge and Spartan Red Team. It had been duplicating Professor Ellen Anders' transponder signal to lure in the UNSC forces and infect them. After the Proto-Gravemind was destroyed, the Spirit of Fire's forces were able to detect Anders' real signal[5] and follow it into the shield world itself.[7][8] Its remains were destroyed when the Etran Harborage was destroyed by the UNSC Spirit of Fire shortly thereafter.[9]

Various human faces from left to right: being absorbed, recently absorbed, absorbed, slightly decayed, moderately decayed, severely decayed.

During the Battle of Installation 04, John-117 found a Proto-Gravemind aboard the Truth and Reconciliation. It is possible that the Proto-Gravemind would have allowed the Flood to use the Truth and Reconciliation to spread beyond Alpha Halo. This Proto-Gravemind assimilated Captain Jacob Keyes and attempted to learn from him the coordinates of Earth. Keyes fought with every ounce of willpower he had to prevent the Flood from gaining this information, burying the knowledge deep down within him and forcing the Proto-Gravemind to systematically discard every other memory he possessed. John-117 arrived at the Proto-Gravemind just before the Flood form was about to finally extract the memory it wanted, and punched through the Captain's skull in order to retrieve his neural implants, thereby robbing the Proto-Gravemind of the knowledge of Earth's location for good. The Proto-Gravemind was destroyed shortly thereafter by the Covenant Special Ops as it was no longer present when human forces captured the ship.[10][11]

Another Proto-Gravemind was observed on the Covenant ship Infinite Succor at around the same time. This one appeared to be made up of Unggoy, Sangheili, human combat forms, and even animals from the ship's hunting preserve. The form was constructed in the ship's engine room, near the core, probably because the command center of the ship was not accessible to the Flood. This form was destroyed by Rtas 'Vadumee before it could pilot the Infinite Succor out of the system.[4]

Yet another Proto-Gravemind was present on the prison ship Mona Lisa shortly after the destruction of Installation 04. Flood on board the ship were attempting to access the ship's FTL drive by collecting and absorbing the knowledge of UNSC pilots into this Proto-Gravemind. It was destroyed when Ngoc Benti killed it with fragmentation grenades.[12]

After Voridus of the Banished released the Flood from High Charity's crash site on Installation 00, a Proto-Gravemind formed nearby. By the time Banished forces discovered the Proto-Gravemind, it was very close to becoming a Gravemind. The Proto-Gravemind was attacked by Banished forces, aided by the Ark's Sentinels and eventually a Retriever Sentinel. The Banished and the Sentinels managed to kill the Proto-Gravemind before it could become a Gravemind and the Sentinels were able to contain the Flood outbreak once more.[13]


  • In Halo: Combat Evolved, plasma grenades do not stick onto the Proto-Gravemind's surface. This is because the Proto-Gravemind is part of the level's BSP geometry.
  • The Proto-Gravemind in Halo: Combat Evolved cannot be damaged in any way.
  • In Halo: Combat Evolved, if one looks carefully, the Proto-Gravemind does move slightly in its place, but not enough to show up on the motion tracker.
    • The real reason it doesn't show up on the motion tracker is that the Proto-Gravemind is not a biped but a scenery object.
  • The Proto-Gravemind in Halo: Combat Evolved has seven tentacles.
  • When the Proto-Gravemind in Halo Wars is destroyed, it will spurt liquid everywhere. It is possible that Flood biomass functions like a water balloon, having a solid exterior and being filled with liquid. This is why sniper rifle rounds have little effect on combat forms: the rounds simply pass straight through the liquefied insides, dealing minimal harm to the combat form.
  • Ironically, the Proto-Gravemind was originally called "The Librarian".[14]
  • In Halo Wars, if the player builds up their forces all the way, the Proto-Gravemind is fairly easy to destroy even without killing all of the Flood colonies, at least on the lesser difficulties.
  • The Proto-Gravemind in Halo Wars is simply referred to as Flood Boss and is not identified within the game as a Proto-Gravemind. As the Flood are a complete unknown to the UNSC forces in the game, characters also just call it "the creature."


List of appearances[edit]