According to Vegapunk, there was once a highly advanced Kingdom 900 years ago, just like Egghead, had technology way ahead of its time. Although it is currently unknown if it has anything to do with the Great Kingdom. However, the technology from 900 years ago disappeared after the war only for Vegapunk to replicate them.
A giant robot known as the Iron Giant was created during the Void Century. For unknown reasons, it attacked Mary Geoise 200 years ago but soon ran out of energy.
The robot is now in Egghead and remains inactive to this day. According to Vegapunk, the robot runs on a power source that can’t be replicated today but was common in the Void Century. It is currently unknown what this is. But there is a pretty convincing theory. The power source can be “Music.”
Why Music?
Luffy’s Gear 5 has the drum beat, it awakened the robot but only a little, as it wasn’t a full song, like say, Bink’s Sake.
Vegapunk could not scientifically recreate the energy source, but music is thought of as more of an art than a science, so its likely it didn’t cross his mind to try music.
While we all know music is an important part of the One Piece world, its unclear as to why. Only that it brings happiness to people. The idea that music truly is real energy in the One Piece world would support this theme as powering the robot would directly help towards liberation.
There is also the connection between the energy source and fire. For example, the fire festival in Wano is a traditional event, so it could be connected to this. There have oftentimes been a fire when partying and music has been played too.
Maybe the more music there is the more powerful the robot gets. When the music fades, the robot’s power fades. This could be why it powered up 200 years ago as it heard music, but as Mary Geoise is so high up, it couldn’t hear it anymore.
Lastly, we don’t know where the robot was prior to attacking Mary Geoise, it could have easily have been located at a place with music playing.
Thoughts?