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Irregular Echinoid Fossil (Heart Urchin) 3D Model
Sea urchins belong to the group Echinodermata, which is one of the closest invertebrate relatives of the vertebrates (including humans!). Living echinoderms are also represented by sea stars, brittle stars, crinoids, and sea cucumbers, and there are many more weird examples in the fossil record. Echinoderms are bilaterian animals, which means they show two-sided symmetry, but they often have a “five-ish ness” superimposed on top, creating a star-like shape from the ambulacral areas. In this heart urchin, the five ambulacral areas host paired tube feet, which help with breathing, feeding, and movement.