The Hunter (Halo 2:A version).

The Mgalekgolo (Ophis congregatio, meaning "serpent union"), is a gestalt of Lekgolo, which are small worm-like creatures that group together to exponentially increase their intelligence, strength, and maneuverability. Of the myriad Lekgolo collectives, the best known is the Mgalekgolo or Hunter, a bipedal form that is used for heavy assault. Ironically, the Mgalekgolo is among the least common Lekgolo configurations, but due to their formidable combat capabilities they are most commonly fielded by the Covenant. While the term "Mgalekgolo" is formally limited to this particular type of Lekgolo gestalt with the other forms having different names, it is sometimes applied to other Lekgolo colonies as well, such as that used to operate the Type-47 Scarab


Source:http://www.halopedia.org/Mgalekgolo