These large larvae slowly crawl across the ground and walls in select areas of Brinstar, and are often remembered for their transparent shell casings that they leave behind after molting. These chrysalis casings can be found attached to a variety of locations, be it in on the walls, ceiling, or on the ground even in shallow water.
Zeros are easy to avoid since they move very slowly. Ice Beam weaponry can be particularly useful to freeze or kill them in their tracks, but they can also be eliminated with a single Missile.
Although their full metamorphosis wasn’t shown in Super Metroid, games like Fusion and Other M showed that the Zeros are the larval form of the Kihunters.