A group of extinct sea urchins that had flat, coin-shaped bodies and lived on the ocean floor.
From Latin 'clypeus' (shield) and Greek 'asteroeidēs' (star-like), combining to describe the shield-shaped appearance of these ancient marine creatures.
These fossils are so perfectly preserved that scientists can see the tiny tube feet that helped them move and eat—they're like ancient coins that once crawled across the seafloor!
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