Category: 
In order to obtain these skulls you have to begin the level from the beginning in either Normal game play or a higher difficulty. However keep in mind that you do not need to finish the level when searching for Halo 3 Skull locations or carry the skull after picking it up. So if you find a skull you can simply save and quit, but this does not obtain for the IWHBYD skull. You can also resume solo or a Co-op game to resume the level and continue looking for these skulls.
There are two different skulls that can be acquired, there’s the Gold Skulls and the Silver skulls, however there are many Halo 3 Skull locations where each and everyone is found.
Gold Skulls Include: Iron Skull, Black Eye Skull, Tough Luck Skull, Catch Skull, Fog Skull, Famine Skull, Thunderstorm Skull, Tilt Skull and Mythic Skull. These gold skulls grant achievements, and if you collect all 9 of them you will unlock the Hayabusa Armor. These skulls also affect the difficulty of game play and allow to make the game more challenging.
Silver Skulls Include: Blind Skull, Grunt Birthday Party Skull, Cowbell Skull, IWHBYD Skull A.K.A I Would Have Been Your Daddy Skull. Silver Skulls do not unlock any achievements, but they do however add multipliers to your meta-game score. These skulls do affect the psychics, dialogue and appearance of the gameplay.
There is also a skull that is called the “Unknown Skull” and has been listed as neither gold nor silver and as of yet has no effect that has been seen.
All Halo 3 Skull locations vary and each skull has a different effect. These skulls are also known to be a big hidden secret for most gamers. There are however walkthroughs that are available to you online that can help you to locate each and every skull so that you can continue unlocking something that’s different and exciting. So now’s your chance to find each and every skull and find out what each one has in store for you.