Final Fantasy VII
Huge Materia are a special type of Materia manufactured by ShinRa in the depths of their Mako Reactors. They are much larger than conventional Materia and house extreme levels of power. Once ShinRa decide that Meteor posed a genuine threat, they devise a plan to use the Huge Materia's power against it.
Their idea is to place the four Huge Materia together and use their power against that of Meteor. This would happen by placing the Huge Materia in the Space Rocket at Rocket Town and ramming the rocket into Meteor, turning it into a Huge Materia Rocket.
Four such Materia are readily available and they need to be gathered from different parts of Gaia. However, Cloud and his group become aware of their plans and attempt to stop them.
The Huge Materia Locations
ShinRa developed the Huge Materia in Mako Reactors found at Corel, Fort Condor and Junon. Where the fourth Huge Materia was developed isn't known, because ShinRa manage to store it on the rocket before Cloud's group were made aware of the plan.
Each of the Huge Materia can be obtained through mini-games in these locations, but even if they aren't obtained the story still progresses anyway. If the player is successful, they are stored in Bugenhagen's observatory for later usage.
FF7 Huge Materia Code
Once the player comes into contact with the fourth Huge Materia on the Rocket, they end up in space. While in space, the player must input a passcode for the Huge Materia in order to obtain it.
The correct code is Circle, Square, X, X. However, even if this isn't obtained the rocket still collides with Meteor and is unsuccessful.
How Do You Get Bahamut ZERO?
If Cloud has obtained both Bahamut and Neo Bahamut during the course of the game, by examining the blue Huge Materia in Bugenhagen's observatory, he can receive the Bahamut ZERO materia, which is an extremely powerful version of the Bahamut Summon.
For more information on how the Huge Materia can be used after they are acquired, please see the glossary entry for Master Materia.