There is many silver skulls, look up a tutorial.
Get all Gold & Silver Skulls.
The first skull on halo 3 is a silver skull. Silver skulls do not award any achievements.
there is 13 skulls 4 silver and 9 gold (the gold you only get the acheivments for).
Because its a silver skull. The silver skulls in halo 3 don't have achievements only the gold skulls do like iron and mystic. Hope i helped.
Sorry there arn't any, The only skulls are in "Halo 3" Which are used in "Halo 3 O.D.S.T."
I'm too bothered to write it myself so... http://www.halo3planet.com/halo-3-skull-locations/ Go down to the bottom where it says Gold Skulls and Silver Skulls. Click on one of the links below it, and it should tell you.
Go to Campaign in The main menu, then hit X when the screen loads. The gold skulls are achievement ones, the silver ones are just silver skulls.
There are 13 campaign skulls ( 9 gold ones which unlock achievements and 4 silver ones which make the game more fun ) and 6 mythic skulls ( 3 for the halo 3 mythic pack and 3 more for the halo 3 odst mythic pack )
They are skulls. idiot.
you can get all of the skulls on multiplayer. =)
ok, go to youtube and type in "how to find all halo 3 skulls" then watch the video and get the skulls. yes, its that simple.
You can use that during campaign scoring mode along with other skulls to rack up points more easily... if they are not silver skulls. silver skulls are used to just have fun during campaign mode.