The second mission of Halo Campaign Evolved, simply titled 'Halo,' tasks players with rescuing stranded Marines after crash-landing on the titular ring world. Amidst this rescue operation, players can also uncover a total of three skulls and one terminal. Some of these collectibles require specific actions, such as utilizing grenade jumps for access.
The Forgotten Terminal
After receiving a Warthog from Foehammer, players will be directed toward the mission's objective markers. Drive the Warthog toward the objective, and you will eventually enter an underground structure. Inside, follow the path by taking a left, then a right turn. After crossing the first road bump, look to your right to spot a large window. Exit the Warthog and jump through this window. A ledge can be found behind you, holding the terminal. 
The 'Give & Take' Skull
This skull's effect drains player shields when firing a weapon, but recharges them when dealing damage to enemies. To find it, proceed to the rightmost of the three reported lifeboat crash sites. Before entering a narrow gap in the cliff marked by a purple torch, look to your left for a stream leading into a cave. Drive into this cave, and partway down, you will see green fireflies in the air near a large rock. Exit your Warthog and inspect the far side of this rock to locate the skull. 
The 'Floor is Lava' Skull
This skull inflicts continuous damage on players when they touch the ground. To find it, continue towards the rightmost objective. You will enter a large, open area with several rocky formations. Make your way to the back of this valley, where a Marine will offer a sniper rifle. Position yourself at the edge of this rock and look towards the burning lifeboat. Below you will be another large rock formation. Carefully inspect its crevices for the skull. Jump down to retrieve it. 
The 'Grunt Funeral' Skull
The 'Grunt Funeral' skull causes Grunts to explode in a burst of plasma upon death. For this collectible, head to the leftmost objective. This area features a tall Covenant structure with Marines located underground. The skull is found by climbing to the middle of the large structure. Ascend the ramp and find a diagonal section of the structure you can walk up. Reach the top of this section and turn around. The skull rests on a ledge on the opposite, more vertical side of the structure. Achieving this requires a grenade jump: throw a grenade at your feet behind you, and just before it explodes, jump. With proper timing and angle, you should gain enough momentum to land on the ledge containing the skull. 
