The Lobed Comb Jelly
You’d think this is some type of bioluminescence, but these awesome rainbow jellies achieve this magical effect simply because their little groups of cilia (aka: combs) diffract light as they move.
Some of them do, however, produce secretions that luminesce separately from this light scattering phenomenon when their photoproteins are activated. But you can only see their greenish/bluish bioluminescence in the dark, and it’s not nearly as cool as this rainbow rave party they’ve got going on.
And now go watch what it looks like when these things move. It’s really cool, I promise.