Boss items are craftable items that are used to summon certain bosses like the Penguin UFO and the Inactive Robot.

Specific boss items can be crafted in different places, for example, the Distress Beacon  is crafted in the Wooden Crafting Table and the Inactive Robot is crafted in the Metalwork Station.

Every boss item has its own crafting recipe, the more you progress and kill bosses the harder it gets to craft the item and defeat the boss.

When defeating a boss, the boss drops an item that makes the player progress deeper into the game, thus raising the difficulty of the game and bosses.