The Diadematacea are a superorder of sea urchins. Unlike most other sea urchins, they generally have hollow spines. The tubercles on their tests are perforated, and most species possess gills.
Superorder
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The Diadematacea are a superorder of sea urchins. Unlike most other sea urchins, they generally have hollow spines. The tubercles on their tests are perforated, and most species possess gills.
==References==
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