Terminal and Skull - You’ll reach an interior room where you fight a metric ton of the Flood. This room has turrets at one end and a walkway above on either side, one of which you drop off of when you enter the room to initiate the fight. Just check behind the wall on the lower level of the room to your left as you enter, before grenade-jumping up to the ledge on the far side where the skull resides. In this same as the terminal, from where you enter, you want to grenade-jump onto the opposite high walkway and look to your left in the corner for this skull. Check the video at 06:43
for the terminal and Famine skull.