>>7736675
Look at the side of the eye. You see how it gets darker as the skin goes further into the eye socket (because not as much light reaches it), and the skin only gets brighter at the eyelid, as it's closer and not as far back into socket?
In this drawing >>7736632 you see skin at the side of the eye that's brighter than what's further right, and so it looks like there's "normal" skin that's not the eyelid, which isn't something humans have.