The Seacons were the last gestalt team added to the Transformers toy line. Introduced in 1988, the team consisted of Overbite, Nautilator, Scalor, Seawing, Tentakil, and team leader Snaptrap, and combined to form the giant robot Piranacon. They all transformed from robots into sea monsters, usually robotic sea animals with legs and forearms attached to make them amphibious. In addition, all the Seacons except for Snaptrap could transform into quasi-Targetmaster weapons, which could stand alone or be wielded by Piranacon.
The Seacons appeared prominently in the Japanese "Transformers: Masterforce" cartoon, starting with the very first episode. They were, with the exception of their leader Snaptrap, mindless drones who cloned themselves endlessly and were destroyed just as easily. Their Piranacon form (called King Poseidon in the dubbed cartoon) wasn't introduced until halfway through the series.
The Seacons were introduced in the American Transformers comics beginning with issue #47 and played a major role in "The Underbase Saga".