How is Tekhelet produced?

How is Tekhelet produced?

Murex snails possess a gland which contains the source of Tekhelet. Dibromoindigo, which originates from glandular secretions of a fresh snail, bonds chemically to wool when put into solution in a reduced state (vat dyeing). In the presence of sunlight, the dibromoindigo debrominates to indigo, leaving color-fast blue wool.