The pig iron mine signifies the first step toward interplanetary organization. As the main provider of pig iron, it is essential for the blast furnace to produce metal as well as for upgrading buildings which require strong vibration resistance. Pig iron is only found in the deeper layers. By upgrading to higher levels, a deeper layer can be reached, which results in better extraction of pig iron. Because every level requires greater use of materials and technology, the production costs will therefore also increase for each level.