Coenholectypus planatus echinoid from the Walnut formation of Texas

This round echinoid is Coenholectypus planatus echinoid from the Walnut formation of Texas (Cretaceous, Albian stage). It is one of many that I have received from a friend who collects in the Lone Star State. The test is round when viewed from the dorsal or ventral sides and shaped like a dome when viewed from the sides. In like it would have been covered with many small spines, the bases of which you can see preserved. I think this is considered a "regular" echinoid due to it's shape. Based on the shape of the test and small spine bases I think that C. Planatus would have lived in the littoral zone in rocky and sandy areas.

Adoral surface

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Oral surface