It turns out that the fact that mantis shrimp have 12 different color receptors in their eyes means they can see... 12 colors. They can't combine the input from

It turns out that the fact that mantis shrimp have 12 different color receptors in their eyes means they can see... 12 colors. They can't combine the input from the different color receptors into a spectrum like we and other vertebrates can. Their eyes even perceive different things in different regions of the compound eye. It's a surprisingly limited visual system for all its supposed extra capabilities compared to ours, which to your point makes "seeing like a mantis shrimp" even more inscrutable from our POV.