Cavemen
From Halopedia, the Halo wiki
On the Halo 3 level "Sierra 117", you can find a family of cavemen.
To find the family, go past the point where Johnson's Pelican gets shot down. You will see a concrete column with the number 3 on it. When you stay beside the left wall and go as high as you can, you must turn around and you will see the cavemen against the wall. The largest of them is holding a teddy bear. Although you can try to shoot them, a death animation for them has not been made, so they will remain idle if you kill them.
The reason they are there is becuase Sierra 117 takes place in Africa which is where humanity is believed to have evolved and which is why the monkeys have human(ish) faces instead of primate faces.
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