Phoenix Logs/Banished Units/Hunters
From Halopedia, the Halo wiki
A bonded pair of walking tanks formed from colonies of worm-like aliens.
Hunters are super heavy infantry who fight in bonded pairs. Their massive shields help protect them from all frontal attacks, and their assault cannons deal heavy damage to any ground target and to vehicles in particular. Hunters can be upgraded to equip beam cannons which fire a constant stream of energy at a target.
Hunters are actually just one form taken by Lekgolo worm colonies, with other notable examples including the musculature and control systems for the Scarab and Locust. Always cryptic and undecipherable, Lekgolo in the service of the Banished seem curiously aggressive and the Brutes take great care to separate them from the general population of thralls and mercenaries under their banner to avoid unnecessary carnage. It's possible the Hunters' service is not voluntary, though only Atriox's inner circle knows the truth.