From Halopedia, the Halo wiki
Hunting rock is a simple Unggoy game where each participant kills a small or medium sized creature, such as a Scrub Grub, by throwing a rock at it. Each kill is marked based on how difficult or easy it was to kill the creature. A Huragok named Lighter than Some used one of the rocks to kill a human named Henry Gibson in defense of his friend, a Grunt Deacon named Dadab.
List of appearances
- Halo: Contact Harvest page 90