Tyrian purple (colorant)

Purple or reddish dye historically made by the ancient Phoenicians using mucus from the hypobranchial gland of either of two species of sea snails.This dye is a rare animal-produced organobromine compound, which the snails make using a specific bromoperoxidase enzyme that operates on dissolved bromide in sea water. Used in Greek and Roman times for dyeing togas and in the Middle Ages for decorating manuscripts. The mollusks secrete a yellowish liquid that oxidizes to a purplish red in bright sunlight; each mollusk only produces one drop of colorant so large numbers were needed to produce enough dye for an entire cloth, making the dye was very expensive.