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1 .This is Scientific American 60-Second Science. I'm Sophie Bushwick. Got a minute?
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2 .Flawless pearls are among the most symmetrical spheres with biological origins.
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3 .But how do they get so round?
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4 .Turns out they turn.
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5 .Pearls form when mollusks such as oysters create so-called pearl sacs around intrusive pieces of grit.
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6 .The sac coats the irritant with layers of smooth nacre, also known as mother-of-pearl.
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7 .The growing pearl rotates itself,
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8 .which allows the nacre to deposit evenly over its surface.
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9 .By examining pearls under a fluorescence and a scanning electron microscope,
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10 .researchers discovered that the surface actually has a saw-tooth texture.
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11 .As the mollusk moves, the pearl is jostled to the next tiny tooth.
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12 .The work is published in the journal Langmuir.
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13 .A pearl's motion influences its nacre coverage, and thus its final shape.
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14 .Depending on its surface pattern, it might turn in a single direction to create a drop or ring, or rotate more freely to form a sphere.
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15 .If a defect prevents this motion,the final product will be shapeless.
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16 .The resulting asymmetrical pearl is doomed to be booed. Roundly.
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17 .Thanks for the minute, for Scientific American 60-Second Science. I'm Sophie Bushwick.
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