Pod infector

Description
The Flood Infection Form, the first stage of the virulent Flood xenoform, is the most commonly seen stage of the Flood and the form that infects lifeforms to spread the Flood infection.

Overall Evaluation
Physically, the Infection Form initially seems rather weak. They can move at a reasonable speed, but don't appear to have any strong physical attacks. Contradicting this, the infection forms are able to breach the Master Chief's armor, which is very hardened and difficult to penetrate. Also, they are capable of tearing apart the Forerunner-crafted containment doors in the facility on Installation 04. The Flood Infection Form appears at first glance to be repulsive but harmless, but once it gains physical contact with a biological host, it becomes very dangerous. Shield Systems negate the effect of the infection form by causing it to explode on contact in a small, damaging cloud of gas. However, if there is no shield system present on the target, the infection process begins. Small tentacles underneath its "body" penetrate the skin, tap into the victim's spinal cord, and unleash an attack on the host's nervous system via direct contact with the spinal cord. Once this is accomplished, it rewrites the neural pathways of the victim's brain with it's tendrils, forcing a resonant frequency match between its neural signals and the host's. Then it releases the Flood Super Cell which overwrites the host DNA and causes rapid mutation. The creature being infected during this process is still alive but has no control during this process. After this is accomplished, it starts to edge its way into the body, liquefying the organs to create the tentacles on the left hand from the calcium obtained and finally nest itself within the chest cavity of its host. After liquefying the insides, it will begin to liquefy the outside body to harden, making a very hard "carapace". If a match cannot be obtained, the host will be left alone by the Infection form, although it is likely that the Flood will eliminate it (if it is not already dead) and save the host's body for later sustenance.

At this time, the only known human subject to be incompatible with Flood Infection Forms is Sergeant Johnson, due to his supposed contracting of Boren's Syndrome from the residual radiation of a crate full of Plasma Grenades. According to an UNSC analysis of various Flood forms, the Jackals and Grunts, lacking necessary calcium stores and biomass to mutate into a Combat Form, are instead transformed into Carrier Forms.

Speculation
There are theories on other species immunities to the Flood, such as the Hunter's lack of a central nervous system and nature as an invertebrate colony consisting of multiple eel-like creatures. The invertebrate nature of Drones, along with their hard, chiton exoskeleton would seem to make them immune as well. Also, because of his contraction of Boren's Syndrome, Sergeant Avery Johnson seems to be immune to flood infection. However, it is speculated that could be because he was in the SPARTAN I program.

Here in Halo 3 is a Flood transformation:



thumb|left|300px|A group Infection Forms swarming a host.

Trivia

 * In Halo CE Sgt. Johnson was not able to be infected by the flood. This was originally thought to be because of Boren's Syndrome. However, it was later revealed that he was a SPARTAN I, so his augmentations may have prevented infection.
 * In Halo CE you never actually see a host being transformed, they are just killed.
 * Infection Forms are carried and supported by Carrier Forms and from Flood Growth Pods in Flood-infested areas. Try not to burst these sacs unless you think you can take them one by one, or swarm by swarm.
 * In Halo 2, the sound files for the Infection Forms from Halo: Combat Evolved were remade, but in Halo 3 they were changed back to the original ones from Halo: CE, but their death noise is different form Halo: CE than just a popping noise.
 * The Infection Forms sound like a distorted Human moan.
 * The Infection Form has appeared in two Action Figure sets: the Halo 1 Flood Carrier Form Action Figure and the Halo 2 s8 Master Chief v4 Action Figure. The differences between the two versions were significant, namely the first Infection Form featured a detachable membrane that revealed the internal organs of the creature.
 * In Halo: Combat Evolved, the Infection Forms glow in the dark in an on-off fashion.
 * An Energy Sword will not lose energy by killing Infection Forms.
 * The Tank Form has the ability to spit/vomit out Infection Forms.
 * Infection Forms do not add to your meta-score when Campaign Scoring is activated.
 * Infection Forms operate in a similar fashion to the Facehugger Xenomorph from the Alien franchise.
 * In Halo: Combat Evolved, when the player shines their flashlight on an Infection Form, the Infection Form will scurry out of the light.
 * The Infection Forms in Halo 3 float in water, and they cannot infect corpses that are in water ponds because of this animation.
 * In Halo: Combat Evolved, Infection Forms can latch into Shade turrets, causing the stationary gun to fire off-target. Killing the Infection Forms causes the Shade to fire properly again.
 * In Halo 3's Theater mode, if you detach the camera and go to a swarm (eg. on the level Halo) it'll look different close up then it will farther away.
 * In the Halo 3 Campaign, if you shoot the pulsating Flood sacs on most Flood levels; Infection Forms will pop out. However, Isolation is an exception because it is a multiplayer level and the sacs have no infection forms in them. Instead, they merely scream and develop a rip similar to the rip seen on normal sacs.
 * If an Infection Form leaps on an unshielded player in Halo: CE and Halo 3, the player will lose some health and the Infection Form will leap off and attempt to get back on.
 * When an Infection Form leaps on an unshielded player in Halo 2, the player will die instantly.
 * During the Halo: Combat Evolved level Keyes, at the point when Carrier Forms are seen coming out of a lake of coolant, when the Infection Forms leap on the Hunters they cause them to shed large amounts of blood, but they not die until a large amount have jumped on the hunter.
 * In Halo: The Flood, an Infection Form almost infected John-117.
 * An Infection Form's tentacles can be seen sticking out from a Combat Form's chest cavity.
 * When Meta-Game scoring is turned on, shooting the protruding tentacles of a Combat Form counts as a head shot and kills the Flood from instantly.
 * Also, Infection Forms give no Meta-Game points.
 * Infection forms have a hole on the bottom, as seen in Jenkins' mission recording.
 * Infection Forms subdue their victims by driving a penetrator into their body and touching the spine effectively blocking nerve impulses to the legs.
 * In Halo CE, if you hit a infection form with a warthog, it would blow up and not cause any damage. In Halo 3, hitting the infection forms does not do anything to them.
 * In Halo 3 some players call infection forms "speedbumps" because hitting them with a Warthog at full speed will sometimes flip a Warthog.
 * It is said the flood may have been the reason the "infection" gametype was created.
 * Although it shows Brutes, Elites and Marine soldiers being infected it never shows grunts or jackals being infected in all of the halo games, because they cannot be infected because they lack biomass and only serve as food for building the flood hive.
 * According to the book Halo: the Flood, the Infection Forms make a "meep" sound.
 * One Flood Spore can destroy a entire species, according to Rtas 'Vadum.
 * Infection Forms bear a resemblance in their ways to the Shadow Leeches from Bionicle, as they both change people into different beings.