This is the smallest and compact engine in the Underwater world.
It can be attached to a Cog and spin it at small speed.
If you tap the engine, its energy is increased and the rotating speed increases. The stored energy depletes over time.
Upgrade increases the cog rotating speed permanently.
To relocate the engine press-and-hold it until the drag button appears.
Can also be attached to the Gearbox, and the rotation speed will be increased 10 times.
If nearby the Atlantis crystal, works 100 times faster