Supraland Six Inches Under All Skull Locations Guide

Hints for the general location, continue for full spoilers.
General tip: [spoilers]Most of them are up high, look for pipes [/spoilers]

hints in no order:

Lava: after something dangerous
Bank: near paint machine
Mines: near the medic
Cage Town: You pass it on the story
Industrial: up high
Beach: you probably aren’t smart enough for this one.

1 Bank: hole in the wall above the building with the paint machine
2 Cage Town: on the way to the elevator, first one I found
3 Beach: on top of the white rock near the anvil and two gold pylons
4 Lava: get to the top floor, press the button, then kill all the monsters. Need to be able to bounce on beam (jump and press CTRL).
5 Mines: on some high rocks near the medic building
6 Industrial zone: magnet up the pipe that comes from Cage Town

1 Bank: hole in the wall above the building with the paint machine. By the “square” button that is one of the buttons to open a door. Small crack on the right just after it, follow the path around to the right.

2 Cage Town: on the way to the elevator, first one I found. Off to the left.

3 Beach: on top of the white rock near the anvil and two gold pylons. You need to attach the beam to the front of the metal bar that slides back and forth. Stand on top of it and let a green orb roll off it then trigger the pull on the beam. If you time it right it will launch the green orb across to the top of the white rocks. Before it falls off teleport and grab the skull.

4 Lava: get to the top floor, press the button, then kill all the monsters. To get to the 2nd floor use magnet launch on the guys with the big axe. Once up there kill all the flying guys. Pull two shield enemies from the third floor and connect a beam between them. Jump and press CTRL to bounce on the beam to the top floor. Press the button then kill all the enemies, skull is in the door.

5 Mines: on some high rocks near the medic building. Exit the medic building and turn right, it is up high on some rocks. The detector helps on this one.

6 Industrial zone: magnet up the pipe that comes from Cage Town, just keep going up and once you find the chest it is off to the left even further up in a small crack.