Sea Urchins
Synonyms
Clypeasteroida
Clypeasteroidas
Dollar, Sand
Dollars, Sand
Echinoidea
Echinoideas
Sand Dollar
Sand Dollars
Sand-Dollar
Sand-Dollars
Sea Urchin
Urchin, Sea
Urchins, Sea
Somewhat flattened, globular echinoderms, having thin, brittle shells of calcareous plates. They are useful models for studying FERTILIZATION and EMBRYO DEVELOPMENT.