Blue-black Urchin (Echinothrix diadema) ガンガゼモドキ – Wana – size 10cm test
The Blue-black Urchin is found in very shallow water exposed to waves. Juveniles are black and white banded. Kauai 2020
Blue-black Urchins have stout spines that are good for wedging. Kauai 2011