The mollusc was one of the two major shellfish sources of the dye, which formed an ancient trade that was centred on the Levantine coast around the city of Tyre in modern-day Lebanon, from where it took its name. The dye’s origin was shrouded in mythology, not least the suggestion it was discovered by Heracles’ dog after it ate the shellfish and its mouth turned purple.
https://www.theguardian.com/environment/2016/dec/05/ancient-shellfish-red-mouthed-rock-shell-purple-dye-vanishes-eastern-med
Dye was a pretty major industry back in the day.