This is the first non-Xyz Wind-Up monster whose effect is not limited to being activated once while it's face-up.
This could be a reference to its effect. Turn the key one way and its level goes up. Turn the key the other way and its level goes down. Activating one of these effects lasts until the end of the turn(the key finishes its rotation at the end of the turn finishing its function). Only being able to activate once per turn means that every turn you are turning the key.
This is the first Fish-type "Wind-Up" monster in the TCG.