Sea Urchins have been roaming the Earth even before the dinosaurs! Echinoids, the family that  sea Urchins and many bottom dwelling sea creatures evolved from,  have been around for about 450 million years, the oldest sea urchin fossil is about 260 million years old! These particular fossils come from Madagascar! 
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The sea urchin fossils available will range in size between 3/4 of an inch across, up to 1 inch across. 
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This listing is for one fossil!