M'galekgolo

Mgalekgolo, more commonly known to Humans as the "Covenant Hunters", serve as large offensive weapons against the Covenant's many enemies. They serve in pairs, and should one fall, the surviving one will go berserk.

They're actually made of many worm like creatures called Lekgolo

Origins Of the Hunters
Hunters sometimes known as San Shyumm Are massive scary guys who will kill you at a moments notice. Your best bet would be to not let them because belive me they will. Like seiously. Remember that one level back in Halo 2 over in Mombassa? Those things were just raging all over the place. It's crazy right? But yeah they're pretty epic. Stay golden everyone.