Pod infector

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.

Description
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. 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.

Immunities/Defenses
Energy 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.

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, which carry even more Infection Forms.

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.



Trivia

 * Infection Forms are carried and supported by Carrier Forms and from Flood Growth Pods in Flood-infested areas. Try not to destroy these sacs unless you think you can take them one by one, or swarm by swarm.
 * 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.
 * An Energy Sword will not lose energy by killing Infection Forms.
 * The Tank Form and Gravemind has the ability to spit/vomit out Infection Forms.
 * Infection Forms do not add to your meta-score when the Campaign Scoring is activated.
 * Infection Forms operate in a similar fashion to the Facehugger Xenomorph from the Alien franchise.
 * The Infection Forms in Halo 3 float in water, and they cannot infect corpses that are in water ponds because of this animation. (eg. on the level Halo) it'll look different close up then it will farther away.)
 * In Halo: The Flood, an Infection Form almost infected John-117.
 * In Halo Combat Evolved, 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.
 * According to the book, Halo: The Flood, the Infection forms make a "meep" sound.