Hexaplex trunculus (also known as Murex trunculus, Phyllonotus trunculus, or the banded dye-murex) is a medium-sized species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex shells or rock snails.
This species is known in the fossil record from the Pliocene to the Quaternary period (age range: from 3.6 to 0.012 million years ago). Fossil shells within this genus have been found in Morocco, Italy, and Spain.
This species of sea snail is important historically because its hypobranchial gland secretes a mucus that most ancient people's of the mediterranean from the Minoans to the ancient Canaanites/Phoenicians and classical Greeks used as a distinctive purple-blue indigo dye. One of the dye's main chemical ingredients is dibromo-indigotin, and if left in the sun for a few minutes before becoming fast, its color turns to a blue indigo (like the dye used in blue jeans)
Photos by George Konstantinou