Halo 3

Sandbox Skull Effect: The Effect of the Sandbox Skull is unknown. There may be no effect whatsoever. Finding the Sandbox Skull will unlock an achievement worth 25GS.

Sandbox Skull Location: The Sandbox Skull can be found on the Mythic map, "Sandbox". This skull is a bit tricky, because it's location is outside of the safety perimeter. Getting to the skull means avoiding death. Create a teleporter node somewhere in the main area of the map. Fly upwards using the monitor and look in the direction of the sun. Turn to the right, past the first pillar, and in between the first and second pillars. The Skull is in this direction at the edge of the map. Create an exit teleporter node, and fly in this direction avoiding fire from the pillars as best as possible, dropping the node directly onto or nearby the skull. You can now teleport directly to the skull giving you enough time to pick it up before being killed by the guardians.

there are a few reasons why they came back

the reason why they were in halo one was that they were being contained until the covenant released them

but in halo two on the second halo they were allready released

so we only wiped them out on installation 04 (halo1) and not installation 05 (halo 2)

Owner42's edit: In Halo 3, the flood are also still alive because many parasites survived from your assault from Halo 2 and Halo 1. These parasites created a new Gravemind. Graveminds are basically just tons and tons of parasites coming together, and they actually have so many parasites they form intelligence. After defeating Gravemind in Halo 2, another one forms, with the same memory and information as the last one- almost as a son or clone.

baigle177's edit: they did not create a new gravemind. gravemind was on high charity, and that is how he got to the Arc, with Cortana.

Then in halo 3 the flood acually built a planet entiarlly out of flood then after you escape the flood you go back and kill the flood for good by lighting the 3rd halo ring.

Disench4nted's edit: They did not build a whole flood planet...that "planet" is High Charity, the Covanant's home world/uber space ship. It was taken over by flood and all of the Covanant on it killed/infected.

Yongblade's edit: Sorry bout that. I thought that when I played Halo 3. Then I played Halo 2 then It came to me.

another reason is because when the halo blow up with the flood that was just a small portion of there army. Pluse they already made the grave mind on High Charity.

the covinant

Actuall, in Halo 3, the Flood that you see are the ones that infected HIGH CHARITY, not from Halo 1. - jtmathlover

edit by Cheesus: round up-- The flood were being researched on the Halo rings, so in the first halo the flood on that ring were destroyed, then in Halo 2 the flood were already released then they took over High Charity and made it their home. Then in Halo 3 they sent a ship from High Charity to Earth they followed Truth and Master Cheif. At the Ark there were no Flood there until they arrived on High Charity and then were all destroyed by the Fourth Halo ring (Version 2) since it was unstable, but there are other Halo rings with the Flood on everyone

YOU CAN NEVER GET RID OF THE FLOOD, IT IS IMPOSIBLE

you can't kill them------well you can but more will spawn

when they first discovered the flood ,the Forerunners had no idea what they were and the flood were most likely from another galaxy and if they are,then they are still wherever they originated from.That means that even if the Halos were destroyed and al the Flood in our galaxy were destroyed,there is still the possiblity of return.And the Flood on the Halos were put there for research purposes by the Forerunners for research purposes.

KR 18's edit:All the installations have flood containment facilities that's why they were there in halo 2.Cheesus, you are wrong.at the end of halo 3 the flood were destroyed.

Its true.You can never get rid of the flood.When the flood first came to the galxy where this game all takes place the forerunners(the original beings that had superior technology far better than human and the covenants)the floods plan was to infect all sentient life in the galaxy.The forerunners fought the flood but knew it was impossible to destroy all of it so they sealed as much of the flood as they could inside the halo rings.Then activated the rings.They managed to stop the flood buy destroying all sentient life in that galaxy.Including them.When the covenant formed up from many alien spieses The leaders the prophets,their guard the elites with their highest rank of houner guard.(the arbiter is not a real rank but more of a death mission person.The brutes third in command butlooking to take over the job of prophets quard,the grunts,weak alone but strong in numbers and need a leader.Then jackals which are treated more as humans would treat a dog by the covenant and the hunters.Massive beings made up of miniscule wormlike creatures that require generous amounts of armour to hold their shape and only travell in pairs.The prophets believe that by activating a halo they will be shown where the forerunners went and learn of the technology thay used to become the most powerfull group in the universe!(breath,breath)