Have you had a chance to see this video from Discovery News showing the flashy ‘disco clam’? A graduate student at UC Berkeley, Lindsey Dougherty, unraveled the mystery of this party-like effect. The clams actually have tiny silica spheres (340 nanometers in diameter) on the inside of their lips that reflect light whereas the outside of their lips is devoid of nanospheres. This is a rather unique method to put on a flashy show in the ocean as other creatures of the deep use bioluminescence whereas these clams just unfurl their lips to reflect the ambient light in the ocean around two times per second creating the effect seen in this video:

Sources:
Discovery News

UC Berkeley Press Release