Heterocentrotus trigonarius

Heterocentrotus trigonarius,^[1] commonly known as the slate pencil urchin or red slate pencil urchin,^[2] is found in the tropical waters of the Indo-Pacific region.^[1] Heterocentrotus mamillatus is a similar, related species.^[2]

Heterocentrotus trigonarius
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Echinoidea
Order:	Camarodonta
Family:	Echinometridae
Genus:	Heterocentrotus
Species:	H. trigonarius
Binomial name
Heterocentrotus trigonarius (Lamarck, 1816)

Heterocentrotus trigonarius can grow to 30 cm (12 in) in diameter (spine-to-spine). The spines are potentially harmful to humans if trodden on.^[2]