Fred Bavendam / Slate Pencil Urchin (Heterocentrotus mammillatus) pair attached to rock wall, Kona, Hawaii

David Hall / Slate pencil sea urchin {Heterocentrotus mammillatus} Red Sea - nocturnal

Norbert Wu / Slate Pencil Urchin (Heterocentrotus mammillatus) spines are stony and used for wind chimes, Hawaii

Jeff Rotman / Spines of Slate pencil sea urchin {Heterocentrotus mammilatus} Red Sea.

Jeff Rotman / Slate pencil sea urchin {Heterocentrotus mammillatus} Hawaii, Pacific Ocean