Thank you, David Campbell! I notice that when I wash a bowl stained with blueberries (Vaccinium spp.), the water is colored blue, then green, then a light yellow as the dye is diluted. Possibly a similar phenomenon to that of shell dyes, though less permanent. The Portuguese man-o'-war (Physalia spp., a siphonophore) yields a similar range of colors when stranded on the beach. Caution is certainly advised in handling them, as the stingers can be painful and dangerous. The purple seasnail (Janthina spp.) yields apparently the same colors on the beach. Is this all one dye? Andrew K. Rindsberg Geological Survey of Alabama