Note the blue underside of their host anemone (Philippines)
Sunlight refracts at odd angles in the waters of cenotes, due in part to the high density and organic material in the water.
Pastel Bells - colorful tunicates (sometimes called "sea squirts"), only an inch long and very delicate. Each has two holes, and they draw water in one and out the other, filtering little bits of food as it passes through.