Colour changes in mucus from hypobranchial gland smeared on cotton cloth. White mucus in gland changes to yellow as soon as exposed to air and light. Subsequent changes shown after ½ hour, 1h, 1½h, 3h, 24h. Similar to mucus of Mediterranean Murex used by Ancients at Tyre to dye emperors’ robes purple. Variation noticed in colours from different specimens, one stayed yellow apart from small area of faint purple, and from mucus on paper.