Where is the Head from the steam trailer??

[Eucalyptus Enjoyer]

I have completed the game and achieved both endings (white and black) and have spent 20 hours combing through what I think is every pixel of this game. I have no idea where the set of puzzles shown in the trailer is, the head rock inside of the profile sky looks to be between the flower area and the mine area. But I can't find a way down, any help is appreciated, good luck if you're still working on completing all the areas of the game.

[TfGuy44]

You have missed a well-hidden area.
The pixels to look for are behind a waterfall.