Jumpmine
From Halopedia, the Halo wiki
Though not an official name, the Brute Landmine can be seen on the multiplayer level Sandtrap. If the player moves outside of the map's border, these mines will automatically eject themselves from a buried position, fly vertically about 2-3 meters above the ground, and detonate in a manner similar to a UNSC M9 fragmentation grenade. The mine itself looks much like a Brute spike grenade without a handle, and is extremely effective against vehicles and infantry.
Since the mine is designed to explode above a target, similar to the old air burst, or a bouncing betty it can shower the crews of vehicles like the Mongoose or Prowler, or regular infantry foolish to venture into the minefield, with explosive debris. The mine is less effective against aerial targets, because it will explode only a relatively short distance above the ground, unless the player is flying relatively low to the ground. The mines can also hurt players even if invincibility is turned on or if they have an Overshield, or if they are in a Bubble Shield or behind a Deployable Cover, similar to the Automated Plasma Turrets in Snowbound. In terms of story value, the mines may have been set up by the Brutes to form a defensive perimeter around the Forerunner artifacts they were digging up in Sandtrap, preventing easy ground-assault. The presence of the UNSC Frigate Aegis Fate overhead, however, circumvented this, and now they prevent ground-based exits.
