How long does the sea snail live?

The ancient method for mass-producing the purple-blue dye from H. trunculus has not yet been successfully reproduced (because the purplish hue degrades too quickly resulting in blue only), but the use of this species has been confirmed in the archeology of Phoenicia, where large quantities of this sea snail's shells have been recovered from inside ancient live storage chambers used for harvesting. Allegedly, 60,000 murex were needed to produce one pound of dye. The dye was highly prized in ancient times. Sometimes known as royal blue, it was prohibitively expensive and only afforded by the highest ranking aristocracy (hence the term "blue-blooded" to refer to aristocracy).