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...

> reminds me of...

As long as we are already on a tangent about rods, cones, and visual perception: one of my favorite fact is that the occasional genetic mutation that creates color blindness in men sometimes leaves a woman with "tetrachromacy". Four sets of rods and cones which increases color perception from some one-million colors to one-hundred million colors.

One fun fact I learned recently.

The cavitation bubbles mantis shrimps create when they strike? We use that same technology to perform direct field manipulation in eye “surgery”. I put it in quotes because I’m not sure if that’s an appropriate word anymore! There is no mechanical slicing! We just place the energy where it needs to be, and thousands of cavitations reshape the eye!

The process is called SMILE.

Wow. That is a worth a glance, folks.

Be thankful we're not mantis shrimp. Color displays and cameras would be such a pain to make