this is a new skull that i just discoverd. on the level delta halo when you finish the gondala ride use the block that is just inside the first door to get on top fo the doorway outside"sputnik skull helps", use a nade to get on the next ledge above that one. the walk around the building to the back and drop down on the ledge,Bingo there is a skull there, and the best part about this is that i am on easy mode!!!!!!, i have yet to confirm its name and use but it is still a Figgin' SKULL!!!!!!!!!!!!!