Mantis Shrimp
A marine invertebrate that at one point was considered to be the animal with the most colorful vision. The mantis shrimp has 12 different photoreceptors. This has since been exceeded by the Blue Bottle Butterfly.
While the 12 photoreceptors were originally considered to grant the Mantis Shrimp 12-dimensional color vision (vs. Humans’ typical 3-dimensional trichromatic vision), more recent research has demonstrated that the visual system of the Shrimp work in a fundamentally different way, such that it performs worse than humans in most regards. [Thoen 2014]