The clypeasteroid order (Clypeasteroida) is a group of sea urchins, several species of which are called "SAND DOLLAR" in English because of their resemblance to a large coin.
This order includes many fossil forms (at least 750 known3), having been very abundant in the Cretaceous and Paleocene. Some, like the Scutellina, are frequent fossils in certain sandstones in the southern Mediterranean. When they die, these sea urchins remain buried in the sediment, which allows excellent preservation during the fossilization process.
