Voldrums are small, ground-based combat robots created by the Alimbic race to protect their facilities in the Tetra Galaxy. Multiple variants of the design exist, as well as several related mechanoids- the Ice, Magma, and Electro Voldrums. Some variety of Voldrum can be found in every facility in the Alimbic Cluster with the exception of the Oubliette. All models share the same basic design- a spherical body with a treaded omnidirectional wheel occupying the lower hemisphere. All varieties of conventional Voldrum are vulnerable to all weapon types, although this is not true of the variant models. Voldrums are almost never found travelling independently- they are deployed from "enemy spawners" when Samus approaches or triggers another security system, usually one or two at a time. The only free-roaming Voldrums can be found in the Frost Labyrinth on Arcterra.
This is the only variety of Voldrum that does not possess any sort of ranged weapon. Melee Voldrums are only encountered twice- in the lower level of the Elder Passage on Alinos, and in the aforementioned Frost Labyrinth. They can attack only by charging directly at a threat- they emit a shrieking noise and begin to wobble immediately before doing so, making this strike relatively easy to evade. Once the pair of spawners that release them in the Passage are destroyed, they never appear there again.
The most common variety of Voldrum, this mechine is physically identical to its melee counterpart save for the addition of two large guns on either side of its body capable of firing short double-bursts of pure energy. These Voldrums can be found in the upper levels of the Celestial Archives, and on Arcterra.
Heavy Voldrums are a tougher, more aggressive Voldrum model found deep within the Celestial Archives and Vesper Defense Outpost. They possess a dull orange wheel section as opposed to the red color of other Voldrums, and fire a spray of energy identical to that produced by the Alimbic Turret v1.4. Although they use a "rapid-fire" weapon similar to the Battlehammer, heavy Voldrums are not appreciably vulnerable to the Volt Driver.
Metroid Prime Hunters
A high-speed rolling robot in nearly constant motion. Equipped with two large guns for attacking from a distance, it is equally efficient at close-quarters combat.