Aquatron

The ocean planet of Aquatron lies somewhere in the Orion Arm of the Milky Way. Long ago, during Cybertron's Golden Age, it was colonized by Transformers, who adapted to their watery world by taking on aquatic alternate modes based on robotic fish and assorted sea life. Notable subspecies include Sharkticons and the Leviacons.

The Aquatronians founded massive automated Energon refineries all across the seabed, maintained by robotic organisms such as the Cleaners. Their uniquely oxygenated mixture of Energon is cheap to produce and extremely efficient. Unlike many of the other lost colonies left isolated after the collapse of the space bridges, Aquatron was eventually found—not by Cybertronians, but by the Quintessons, who annexed the defenseless little world into their Imperium, repurposing the Sharkticons into an army to quell any potential rebellions.

To outside observers, the brutally subjugated Aquatronians appear to be happy and productive Energon traders under the benevolent guidance of the Quintesson's fictional Co-Prosperity Sphere, but dig a little deeper and the Quintesson's web of lies will swiftly unravel.

Transformers: Retribution
Aquatron was eventually found by the Quintessons who conquered the virtually defenceless planet and made it part of their empire. The physician Xeros was posted on Aquatron much to his annoyance. The Sharkticons foresaw a great saviour who would come to Aquatron and free them.

After the Quintessons had discovered that Cybertron had fallen into civil war and had been rendered lifeless, they concocted an elaborate scheme to retake the planet based on Aquatron sending Inquirata to pose as a Cybertronian colonist to greet the Autobots lured there via visions sent to the Matrix of Leadership via the Sharkticon Matrix of Leadership.

When the Autobots arrived, Inquirata posing as "The Curator", claimed Aquatron had no ties to Cybertron or its colonies but was an old ally that was eager to resume trade relations. Rodimus, Kup and Bumblebee smelled something fishy and took a shuttlecraft beneath the surface only to be incapacitated by the Hydratron.

The Decepticons soon arrived in Aquatron's orbit and opened fire on the Ark only for the Quintessons to incapacitate both ships. The Curator then revealed his true nature, the Quintesson involvement and Aquatron's true nature. The Quintessons organized "peace talks" the next day and manipulated events to try and wipe out both Autobots and Decepticons in one fell swoop, condemning Optimus Prime and Megatron to death by combat. The energon spilled from their duel, combined with the Matrix's energies, proved enough to reactivate an Aquatronian space bridge that allowed the Quintessons to warp their Sharkticon forces to Cybertron.

The Quintesson threat however was enough for Autobots and Decepticons to briefly set aside their differences. In the process, Megatron managed to acquire the Sharkticon Matrix and recalled all the Sharkticons to Aquatron to board the Nemesis to serve as his personal army. After his humiliating defeat on Cybertron, Tyrannicon returned to Aquatron where he claimed the Sharkticon Matrix before being killed by the Hydratron.

Meanwhile, Optimus Prime used Inquirata's wand to detonate the space bridge before the Ark and Nemesis left the planet.

Background Information

 * Aquatron is a planet newly introduced in the Aligned continuity family, having not appeared in any other Transformers media besides the Aligned novels.