Pink is one of the extra fun ones. You'll notice that there is no pink in a rainbow, but most all the other colors are there. Even showing things like a bit of all the indigo and purples and blues and oranges as it blends from one bigger color to the next. It's all by reading electromagnetic wave lengths of reflected light and the brain processing it and assigning a color to it. This also means that there's no way to prove that the color you perceive as being blue, for instance, is the same color as what anyone else sees as blue. Your brains version of what blue looks like may be completely different.

But pink. Pink is it's own set of weird. At no point across the visible spectrum of light is there a wavelength size that is pink. The longest visible waves of light are red and it works its way down to shorter and shorter waves until it gets to violet.

So what is pink? An imaginary color your mind made up when it receives wavelengths of the longest area of color (the reds) and the shortest (the violets/purples) at the same time. That's pink. There is no real way for your mind to mix those wavelengths to make any known color, so your mind just says "fuck it" and made one so it could interpret that nonsense.

We can both detect orange light, but the shrimp can also detect red light mixed with yellow light. We get tricked into also seeing orange, despite no strictly orange light being there.

Think of it like sound. If we heard sound like we see light, we would hear a chord as identical to a tone somewhere in the middle of those notes. Mantis shrimp can see chords of light without any mixing, seeing both colours rather than just a colour somewhere in between.

This came out in 2014? Oh man I've been so wrong about mantis shrimp for so long now.

They trained mantis shrimp!? That’s more interesting than the color fact lol

That doesn't justify calling them fake. All colors are made up in our brains. At least call them composite

Isn't brown just a dark orange? I guess it would depend on the exact shade