So, you know how when you refract light through a prisim?
I was thinking, maybe would could have a prismatic creatu. Like, when you hatch an otachie for example, it would say: Congratulations, you have hatched a prismatic male otachie!
The design would be simple though, the base of the body color would be black while a single streak of white is on the muzzle and down the neck. At the shoulder, there could be what would look like a side view of a prisim. After the prisim, the refracted rainbow of light could go off of the body by the flank and tail.
Feel free to do what you wish with this suggestion. I just really hope you use it.
Thanks for your time,
~Blood