Rtas 'Vadum in crashed Flood ship
From Halopedia, the Halo wiki
The Half-Jaw in crashed Flood ship easter egg can be found on the level Floodgate. When you jump down the hole to get into the Flood ship that crashed, there will be a few dead Ultra Elites lying around. The first one you see has SOMETIMES Half-Jaws face. However it is the old model from halo 2.
