Dear, all
 
 
        Have been noticing that certain shells like Bolinus brandaris, Hexaplex
trunculus, Opalia crenata and even the pelagic Janthina balteata produce a
purple dye pigment? or fluid?. My curiosity is whether this pigment? or
fluid?, is an act of defence or is it secreted by the animal when in
stress, since when I collect live animals, they normally never show traces
of this pigment? or fluid? Immediately ?
        Is this purple dye present in many other shells besides these ? Do (or
did) any other cultures use similar pigments like the ancient Romans did ?
        Would really appreciate hearing your comments !!
        My very best shelling regards to you all,
 
        Carlos