The Underwater Metal Extractor is a level 1 naval structure available to both the CORE and the ARM. It extracts metal from underwater metal deposits and adds to the player's metal production a number proportional to the size of the metal deposit, which ranges from 0.8 to 2.3 (maximum), while consuming -2 energy per second. It is an essential structure in water terrain maps and, as it is an underwater unit and cannot be seen by scout units or radar, it is also very useful in maps with underwater metal deposits.