Suzanne Williams

speaker

225 appearances 1 recordings 1 series first heard Jul 2026 last heard 30 Jul

Suzanne Williams’s voice in public audio — every appearance, attributed to the second.

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Recordings per month over the last 12 months — 1 in all, peaking in Jul 2026 with 1.

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In Our Time · Seashells · 30 Jul 2026 podcast

And the dye comes from this tiny specialized organ called the hyperbranchial gland.

And in the wild, these animals are predators.

So they eat barnacles and mussels and they secrete this secretions from this hyperbranchial gland onto their prey.

And it makes them relax, which means that they don't have to drill them.

So it saves them energy to do this.

They also produce these secretions to get rid of predators because it has this muscle relaxing properties.

They also put it around their eggs and it's thought to have antimicrobial properties.

There is no purple dye inside the hyperbranchial gland.

It's a colourless precursor to the dye.

But if you cut it open and expose it to light and sun, enzymes act on it and it will change colour.

You'll see it going from colourless to milky white to yellow-green to green to blue to purple.

The final pigment is called 6,6-prime dibromoindigo.

And it's the bromine atoms, which the snail takes up from seawater, that actually gives huge stability to this pigment.

So unlike other pigments that were available at the time that would wash out in the laundry and fade in the sun, this actually gets brighter and more vibrant in sunshine.

And there's some recipes.

Pliny the Elder recorded a recipe

and mentioned how dreadful the smell was.

And I can personally testify that rotting pigments smell absolutely disgusting.

But layered on top of that, there was garlic, stale urine.

And the numbers they had to process were huge.

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