When first found in the world, the Iron Hulks will be covered with moss and foliage, presumably because they have been dormant for quite some time. They will come to life and attack the player or anything nearby when mined with a Pickaxe. They can also be stirred to life with lightning, which keeps them activated for a longer period of time than if they were mined. During the Aporkalypse, the Iron Hulks will remain activated constantly.
There are six different parts to be found: a head, a torso, two legs, and two arms. The arm and torso are by far the most devastating ones, as they will shoot a giant laser beam that procs small explosions in a straight line, which can cause immense damage, and if unarmored, can instantly kill the player. These lasers will also light structures, plants, and mobs on fire. The head and the leg will perform a smash attack, where they will leap at their target and smash down, doing a small AOE attack that also starts fires, and can proc multiple times if an entity is closer to the center of the attack.
The player can, however, farm Iron Ore by mining them repeatedly. Since their attack AI targets the players location only when they start their attack animation, the player can occasionally hit them when they're still active.
The Large Iron Hulk is a Boss Monster. It is the result of the player activating every piece and leading them all to the same place. As soon as the last piece reaches the pile, the Large Iron Hulk will wake up and the fight will begin. The boss has a variety of attacks, including launching 3-5 proximity mines around the boss, throwing a ball of fire at the player, spinning around firing a laser, and forming a ring of Basalt Eruptions around the boss. The Large Iron Hulk also has a melee attack in which it jams its mouth into the ground, as well as a short range teleport.
Upon death, the Large Iron Hulk will explode and spawn all of the pieces in random locations around the island it died on, excluding the head which will land directly where the boss died. All landmines and basalt eruptions will remain where they are until something destroys them. The Large Iron Hulk will drop 2~4 Gears, 2~6 Iron Ore, 6~7 Infused Iron, as well as the Blueprint for the Living Artifact.
It is recommended to mine the ribs. Although they do the most damage, their attacks are the easiest to dodge. The ribs also have a longer pause between attacks, allowing the player to mine it for longer without dodging attacks.
The biome Iron Hulks are found in are often next to Thunderbirds. This can cause the Iron Hulks to be struck by lightning, awakening them and often wreaking havoc to nearby mobs.
Thunderbirds also don't run away from hulks, thus when killed by one are set on fire and won't drop Thunder Feathers.
The ribs and arm pieces can attack with their lasers in melee range, even if they just attacked at range. Be wary when mining these pieces while they're activated.