The design derive from an icon which indicate 'render'. It is a button that performs rendering 3d images/animation automatically.
A fun fact about this icon is, every time a 3d artist/animator see the button (the icon symbol of kettle), it brings some sort of feelings about experiences and hardship they had as if they are seem to be waiting for a year patiently before an image or animation to be completely done. And that makes a kettle to be worth symbolize dedication for work and hardship.
The design would also be a picture for all who work hard and pursue their learning as they work.