The Bible instructs men to wear fringes on the corners of their garments as a constant reminder of God. Can we trace these holy threads back to ancient times and learn more about their significance? One of the threads of these fringes is supposed to be a particular colour blue - made from the blood of a shellfish. In this episode Simcha and chemist Zvi Koren try to track down the dye using ancient clues and tests them with modern science.