A fact related to something in the ocean, cephalopods have photoreceptors that are oriented neatly with nerves in the back, as you would expect. But mammals have the nerves coming out the front, in the way of the path of light! [1]

So, cephalopods have sensors that match a modern camera that's "back illuminated", with metal layer/routing out of the way, and humans have a old type "front" illuminated sensor [2].

[1] Nice image here: https://www.facebook.com/groups/10150112797390640/posts/1017...

[2] https://www.digitalcameraworld.com/features/what-is-a-bsi-se...