Roman system caused Murex shell to disappear, that way gently wiping out Phoenician's main industry, whose main clients were Romans. It was all about red, that precious vibrant red that marked Roman senators, and all the ones that wanted to look like them. Red as the symbol of power. Now have a look to that very interesting Spanish page, where it's explained that for a single gram of colorant, you needed at least 10.000 live shells. They say the Purple industry stopped in 1495. It's untrue. Murex colorant, due to over exploitation of the shell, had turned too expansive by 6th century. Just by the time Arabs developed a new bright red colorant, surrounded with secrets and alchemy and different names: al-kermes or Kermes or Carmin or Vermillon or Cochineal, the insect. It gave the bright red silks of Granada, the world was dreaming about, like a magical reminding of the Roman's power. That much that after Catholic Conquest of Spain, it was the arabic kermes chosen as the Spanish royal color (that's why Joaquin Cortez didn't brought to Spain the cochineal insect from Mexico). More on Murex shell: http://www.historiayarqueologia.com/2016/10/la-industria-fenicia-de-la-purpura.html