Unlike other urchins, the bodies of many sand dollars also display secondary front-to-back bilateral symmetry, with the anus located at the back rather than at the top as in most urchins.
The anus is located in the back rather than at the top as in most urchins. Unlike other urchins, the bodies of many sand dollars also display secondary front-to-back bilateral symmetry.
Unlike other urchins, the bodies of many sand dollars also display secondary front-to-back bilateral symmetry. The anus is located in the back rather than at the top as in most urchins.
Unlike other urchins, the bodies of many sand dollars also display secondary front-to-back bilateral symmetry. The anus is located in the back rather than at the top as in most urchins.