Hatching from small, pink-white eggs, at full size the Kiru Giru is roughly four times as large as a human. Its segmented, sloped body ranges from blue-green to purple, and features several round nodes running its length, which may serve defensive purposes. Most of its body is invulnerable to attack, save for its bright orange underbelly. While normally sluggish, the Kiru Giru can attack with surprising speed when threatened, using the small legs toward the front of its body to charge at enemies.
When the time comes for it to mature into its Imago form, the Kiru Giru will enter a grey, stringy chrysalis and rapidly metamorphose; within minutes, it is a full-grown adult, and capable of laying eggs.
Samus Aran encountered four Kiru Giru specimens while travelling through Norfair. The first two larvae were free-roaming, and had to be destroyed by using the newly-acquired Wave Beam and several Morph Ball Bombs, respectively.
Later on, she encountered the long-dead corpse of a third larva, in a corridor infested by carnivorous Tangle Vines. It appeared to have been one of the many creatures to have fallen prey to the vines, which had pierced and devoured its flesh from within.
The final Kiru Giru she encountered had been similarly ensnared, and was in the process of being consumed by the vines. However, this one was still alive, and attacked Samus by firing projectiles from its nodes. The only way for Samus to free the larva was to destroy the Tangle Vines tethering it to the ceiling. When the last vine was destroyed, the Kiru Giru plummeted through the floor, where it began to tunnel downward and formed a coccoon around itself. Shortly afterward, it emerged as the Imago, and immediately began to make its nest.
The first two Kiru Giru are encountered in the same room, impeding Samus' progress. Only a layer of stone stands between Samus and the weak point of the first one, and it can be destroyed with just a few shots from the Wave Beam. The second one will actively attempt to charge Samus, but can be driven back by Missiles in a manner similar to Crocomire's fight in Super Metroid. To destroy it, Samus must lay Bombs while the larva is attacking, so that they detonate while the Kiru Giru is on top of them.
The ensnared Kiru Giru is trapped in a curled-up position, hiding its weak spot. To defeat it, Samus must freeze a Winged Ripper flying about the room, jump on it, and shoot the vines that are holding the larva with Missiles; however, it is possible to defeat it without using the Ripper by jumping up and shooting diagonally. Spores are constantly launched from the larva, either as a result of interior decay caused by vines or the latter attempting to reproduce. As Samus destroys the vines, the larva slowly changes from grey to its natural colors (possibly because the vines were absorbing its blood). When defeated, the larva itself will fall through the floor, opening a path for Samus to exist the chamber. An interesting thing to note is that the winged Ripper can be killed if it is directly underneath the Larva the moment it falls, thus crushing it.
- On the official Japanese website for Zero Mission, the Kiru Giru (in all its forms) are referred to as a Giant Evolving Bug.
- The first two Kiru Giru larvae can be killed simultaneously with a single Power Bomb, if Samus encounters the creatures after exploring Chozodia. Likewise, they can also be defeated with a single beam shot to their underbellies after acquiring the Plasma Beam.
- The room containing Kiru Giru also contains the only visible quantities of water in Norfair featured in Zero Mission, although if Samus returns after defeating Ridley, the pools will have dried up. Some rooms in Norfair featured in Super Metroid have water, specifically in the caverns after Crocomire.
- This miniboss seems to pay tribute to Spore Spawn, as the former has a slightly altered version of the latter's theme and both can attack by launching spores.
- The mechanic of firing at the Kiru Giru Larva to push them back is similar to the battle with Crocomire, the Omega Metroid in Metroid Fusion and the Desbrachians. Coincidentally, Crocomire was dropped from Zero Mission.
|Food, Nourishment and Sustenance|
|Plants & Fungi||Blueroot Tree • Fruit • Red Starburst • Sap Sac • Saturnine|
|Species||Geruta • Embers • Kiru Giru • Pirate Militia • Reo • Ripper • Sciser • Scritter • Skree • Space Pirate • Tallon Crab • Torizo • X Parasite • Zoomer|
|Specific Humans||Samus Aran • Virginia Aran|
|Carrion||"Deceased Soldier" • Amok Mommy|
|Liquid||Lava • Phazon|
|Artificial/Misc.||Deca-triticale • Elite Nutrient Mix • Energy • Nutrient-grade biomatter • Synthetic Metroid rations • Wrecked Ship|