When it is idle and no threat is visible, it will gently sway its tentacles around and emit soft hissing and groaning noises. When the Gene Worm is defeated, it sinks back into his portal, but not before emitting a ' portal storm' into the room, similar to the one that occurred as the Nihilanth died. The worm takes damage from attacks hitting a void behind its stomach cavity. This causes it to summon reinforcements by opening its abdominal cavity, which spawns a Shock Trooper. In order to kill it, the player must blind it by shooting both eyes with the mounted laser guns on either side of the worm. The Gene Worm attacks with its tentacles and also ejects a deadly chemical stream from his mouth. It bears a striking resemblance to the Xen Tentacle, appearing to have green skin with many tentacles and possessing a beak-like protrusion similar in both shape and position. Physically, the alien resembles a green, worm-like being with many tentacles.
