Holtz are found in the lower regions of Norfair, and when undisturbed, will quietly hover in midair like armored floating sentries. When intruders get too close, Holtz will repeatedly swoop towards their target, making use of their combusted bio-propellants to generate thrust and quickly rise back into the air. Their short flipper-like appendages are moved to help stabilize their flight orientation, but they also serve as a pair of horns when aggressively ramming into targets. Since they are well-protected from their surroundings, Holtz will even dive into the most lethal forms of lava in order to attack.
Holtz are resistant to standard Missile attack, but can be killed with three Super Missiles. This isn't a very effective attack strategy though, so it’s best to use the most powerful beam weapons (i.e. Plasma) in combination with a Charge Beam, or use a single Power Bomb or Screw Attack, which will kill them in a single hit.
Holtz look quite mechanical in their design with their armor and single lidless eye, but in Zero Mission, they were shown with more slender flippers, a more concealed thruster, and a forked tongue-like organ. It’s unknown whether this “tongue” might act as an additional sensory organ like in snakes, but it makes the Holtz look much more organic than they may first appear.