Cardinalfish
(Apogon imberbis)

Found across coral reefs in the Indo-Pacific, the Cardinalfish has one of the strangest relationships in the ocean. Ostracods — tiny bioluminescent crustaceans — are sometimes eaten by the Cardinalfish, but when swallowed, they release a burst of light inside the fish’s body! To avoid becoming a living lantern and attracting predators, the fish spits them back out like a tiny underwater firework as seen in the gif below!