Any of several sea urchins with purple or purple-tipped spines, especially Paracentrotus lividus of the east Atlantic, Arbacia punctulata of the west Atlantic, andStrongylocentrotus purpuratus of the east Pacific.
Origin
Late 19th century.
Definition of purple sea urchin in US English:
purple sea urchin
noun
Any of several sea urchins with purple or purple-tipped spines, especially Paracentrotus lividus of the east Atlantic, Arbacia punctulata of the west Atlantic, andStrongylocentrotus purpuratus of the east Pacific.