Liz Harper

speaker

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

Liz Harper’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

Whereas things like oysters and scallops, it's very difficult to see that layer.

It's tiny.

So Mother of Pearl is technically called Nacre, and it is one of the very earliest types of shell structure that the mollusks use.

And you find it across almost all of those classes that Suzanne talked about.

So it's a really very important structure.

It shows that beautiful iridescence because it's actually built of...

repeated tiny, tiny layers of a calcium carbonate mineral called aragonite.

And they're about half a micron or so thick.

They're nice hexagonal.

They're, I don't know, often about sort of 10, 15 microns across.

And each shell is built of lots and lots of these on top of one another.

And it produces this great iridescence, probably for some reason that was explained to me in O-level physics that I missed earlier.

So it scatters the light in some way.

It's tremendously important material as far as the mollusks are concerned because it is actually really very, very tough.

So actually, if you think about trying to break something that's made of lots and lots of repeating tablets, then you either have to break each of those tablets in turn or the crack has to skip around them.

And that basically sort of dissipates a lot of cracks that the fish or the crabs may be inflecting on your shell.

So I don't think they have that maker for themselves, for colour to demonstrate.

It's usually covered up by other shell layers or this magic organic layer on the outside.

So it's almost certainly a structural thing that they're using.

But what's really interesting about that microstructure, so it's a really interesting thing that lots of material scientists are very interested in.

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