When plankton crushes ashore, it dies and disintegrates creating foam-like bubbles, which are left at tide pools floor after the ocean retreats. The bubbles display all the same properties as soap bubbles do, displaying typical interference colors, except they last much longer than soap bubbles do.

The organic material of the plankton, that lowers the surface tension of the water (as soap does) and preserves the film is responsible for these colors. It might be also interesting to note how the appearance of my reflection is changing from bubble to bubble. The image was taken at Fitzgerald Marine Reserve.