Schultz, H. (2006). Sea urchins: a guide to worldwide shallow water species. Third edition. <em>Heinke & Peter Schultz Partner Scientific Publications: Hemdingen. ISBN 3-9809868-2-9.</em> XII, 484 pp.[details]
the original juvenile has reached the long-spined stage (4.5 mm) as new eggs are fertilized in the other pouches