From that Wikipedia link, "for scale": > In nature, the snails use the secretion as part of their predatory behavior in order to sedate prey and as an antimicr

From that Wikipedia link, "for scale": > In nature, the snails use the secretion as part of their predatory behavior in order to sedate prey and as an antimicrobial lining on egg masses.[14][b] The snail also secretes this substance when it is attacked by predators, or physically antagonized by humans (e.g., poked). Therefore, the dye can be collected either by "milking" the snails, which is more labor-intensive but is a renewable resource, or by collecting and destructively crushing the snails. > David Jacoby remarks that "twelve thousand snails of Murex brandaris yield no more than 1.4 g of pure dye, enough to colour only the trim of a single garment."