A class of echinoderms that comprises the sea urchins.
- ‘Ophiuroidea is grouped with Echinoidea and Holothuroidea based on the closed ambicular grooves.’
- ‘Clark endorsed splitting L. sexiesperforata from Mellita but Mortensen used the name Leodia as a subgenus of Mellita in his extremely influential Monograph of the Echinoidea.’
- ‘Other representatives from the Echinoidea also display two nonadjacent rRNA genes (with the trnV gene inserted or not inserted).’
- ‘BNip3-related sequences were found in all major lineages of Bilateria, from Echinoidea and Ascidiacea to mammals.’
Modern Latin (plural), from echinus.