Infraclass
Irregularia (Irregular sea urchins)
Dendraster excentricus. Photo: (c) Lee, some rights reserved (CC BY-NC)
Irregularia is an extant infraclass of sea urchins that first appeared in the Lower Jurassic.
Dendraster excentricus. Photo: (c) Lee, some rights reserved (CC BY-NC)
Irregularia is an extant infraclass of sea urchins that first appeared in the Lower Jurassic.