Colour changes in mucus from hypobranchial gland smeared on paper. White mucus in gland changes to yellow as soon as exposed to air and light. Subsequent changes shown after 5 minutes, 15 min, 40 min, 2h 45min, 24h. Similar to mucus of Mediterranean Murex used by Ancients at Tyre to dye emperors’ robes purple. Variation noticed in colours on paper from different specimens and from mucus on cotton cloth.