The Cystoidea or cystoids, are extinct echinoderms that lived attached to the sea floor by stalks, and are distinguished from other echinoderms by triangular pore openings.
The Cystoidea are extinct echinoderms attached to the sea floor by stalks, and are distinguished from other echinoderms by triangular pore openings. Cystoids, are extinct echinoderms attached to the sea floor by stalks, and are distinguished from other echinoderms by triangular pore openings. These echinoderms lived.