The detector tells me that the artifact is in the boulder chase area. I looked at the walkthroughs on this site and they both say it is in the middle of the scene and seemingly quite obvious to see. But I've tried 3 times now to get it and I can't see it at all
Hello! It's me, it's me, I'm as white as can be!!!
If you get squashed too many times, the game automatically advances you to the next part of the level. But if you make it to the end of the tunnel without getting nailed by the boulder, you'll find the artifact piece.