A dark eco tank is a dark eco container located in Metal Head city (scattered around, mostly placed upon tall platforms protruding from the acid in the center) during Jak 3. Jak had to destroy six of these in the mission "Destroy dark eco tanks". These organic containers are filled with dark eco, and act as temporary caches. While they look similar to a plant, they have a transparent dome fitted around them and continuously leak dark eco in both fluid and electric forms. The Metal Heads supposedly used these to develop new weaponry. However, Jak destroyed all six of them during a mission. Destroying the last one granted him the new Dark Jak power, Dark Strike.