Flood carrier form

The Carrier Form is a Flood form used to incubate and spread Flood infection forms. Carrier forms are formed from older Combat Forms, or from infected bodies that are unsuitable for combat.

Overview
Combat forms that have outlived their usefulness or become too damaged to fight will begin to spontaneously generate infection forms within their host bodies. As the upper body swells to grotesque proportions, the limbs of the combat form wither away into stumpy legs and flailing tentacle-like appendages. The Flood form is now unable to defend itself, but still retains enough mobility to move toward potential hosts.

Carrier Forms perpetuate the Flood species by acting as mobile incubators for newly created Infection Forms. If potential hosts are detected, the Flood form will simply waddle within range of them, throw itself on the ground, and expand its incubation sac with gases until it explodes. This detonation scatters the infection forms and can injure or kill potential hosts, with the explosion being comparable to that of a fragmentation grenade.

During the Battle of Installation 05, Carrier Forms were utilized as 'boarding parties' by the Flood. They are ejected from an airlock of an infected ship towards an uninfected ship.

Tactics
Carrier Forms are usually considered slow and of little threat unless they are close to the player. However, one particularly dangerous trait of exploding Carrier Forms is the explosive chain reactions they can cause. A Carrier explosion will cause any other Carrier Forms close enough to explode also. They also cause any nearby explosives or objects to explode. This means a single Carrier can cause a massive explosion through a chain reaction filling much of a small area. This can be used to a soldier's advantage if there are Combat or Infection Forms surrounding the Carrier(s). They are sometimes considered a "Flood grenade".

Any direct explosion eliminates the threat of the Carrier, as well as any Infection Forms that were incubating inside of it. This means that enough needles from a Needler will kill it, or you can throw a grenade at it.

Carrier Forms are one of the easiest enemies to take down. One shot from any weapon, say the Plasma Pistol, will force it to explode. However, there is not a single weapon that can actually blow it up, not even a direct Rocket Launcher. Therefore, this has to be taken into account, strategically. For example, when confronting a large number of Flood, you may wish to destroy the Carrier Forms, which in turn will kill all nearby Flood. First, allow the Combat Forms and other to get reasonably close. Then, use any weapon - preferably one which has ample ammunition - to kill it.

It is not recommended to use sniper rifles against the Flood; it is simply a waste of valuable ammo. In any case, sniper bullets simply pass through Carrier Forms, dealing virtually no damage.

In Halo: CE a good tactic is to hook one with a Plasma Grenade and shoot it with a Shotgun; this will kill the Infection Forms inside. Running over Carrier Forms, on the other hand, is a very bad idea. Their explosions will easily flip your vehicle, wasting precious time.

In Halo 3 it is a good idea to individually lure a Carrier form away from the rest of the flood and then shoot it down, if its done right you can take down a Carrier form with an assault rifle and the infection forms inside just needs accuracy and very good timing. The luring bit needing patience as its quite tricky to lure them out as if you get to close they'll explode, if you get too far they'll just walk away.

Trivia

 * In Halo: Combat Evolved, the level "The Maw" contains a glitch in of which the Carrier Form explodes, but the Infection Forms do not move.
 * The Carrier Form of Flood is the successor of the Simulacrums, from the Marathon series. The Simulacrums were cybernetic humans made to look like the crew of the UESC Marathon, the only flaw was that they all wore green jump suits, making it easy to distinguish which humans were actually Simulacrums. As soon as you were three meters close to them they would explode, heavily damaging or killing the player.
 * Strangely, when shot by the Flamethrower, the Carrier Form will explode and release the Infection Forms, which seem to survive the fire. Possibly the Carrier Form's explosion puts out the fire. This is strange considering that an Incendiary grenade will kill the Carrier and the Infection Forms. The Incendiary grenade does, however, seem to have a small explosive force used to scatter the flames.
 * Carrier Forms are sometimes nicknamed "popcorn", due to how they "pop" and release Infection Forms.
 * Carrier Forms have a slight similarity in physical appearance to the Flood Juggernaut.
 * In Halo: Combat Evolved, a Carrier form can produce short bursts of speed once it spots a target.
 * In Halo 3, a Spartan Laser beam can only penetrate two Carrier Forms. In turn, this will make the Carrier Forms explode without releasing any Infection Forms at all, similar to sticking a Carrier Form with a grenade or killing it with a Needler supercombine explosion.
 * The Carrier Forms form in Halo: Combat Evolved and Halo 2 would release between 4-6 Infection Forms when they explode, but the Halo 3 Carrier Forms would release dozens, but this is leveled out by a smaller and less extreme damage radius.
 * On rare occasions in Halo 3, the Carrier's arms and legs will be left behind upon death. However, this is exclusive to Halo 3 as the arms and legs completely vanish upon exploding in Halo: Combat Evolved and Halo 2.
 * In Halo 3, Carrier Forms can jump.