Sculls
From Halopedia, the Halo wiki
sculls are hidden glicthes on legendary when you find them cool stuff happen like someons head explodes when you shoot their head
http://sjl-static2.sjl.youtube.com/vi/A1mTAddW6SA/2.jpg
1st picture is showing the scull that gives master cheaf camoflouge ps: no light afterwords.