In Biblical time blue dye was taken from an animal known as the chilazon. It is a boneless invertebrate, having a shell that grows with it. In ancient times, animals such as these were renowned for their dyes (Pliny 9:60,61). The Bible commands that a blue string be worn on the corners of the Israelites' prayer shawls, a blue dyed with this extract. The dye is removed from a cyst near the head of the snail, preferably while the animal is still alive. It is boiled with alum as a clarifyer to produce the dye. Only a few drops of dye could be obtained from each snail, and acc ording to one modern researcher, over 8000 snails would be needed to make a single cubic centimeter of the dye. This explains its high cost and its restriction to royalty. Thus the term "blue blood." John from Arkansas