the eye of an octopus
similiar to human
but
no cones (humans use for color)
pupil is square instead of round

instead of cones
octopi have photoreceptors
that perceive polarized light
and the angles it arrives from

polarized vision makes possible
clear vision in water
without distortion of objects
caused by reflections

the square pupil allows
different wavelengths of light
to come into focus
at different lengths
from the lens

the octopi could process
this information
to differentiate colors