"Mespilia globulus (Linnaeus 1758), the Blue Tuxedo Urchin (Sphere Urchin of science). Eastern Indian Ocean to western Pacific... in shallows amongst algae it grazes on. To three inches in diameter. Needs hard substrates, shady areas. Can be kept solitarily or in small groups. Eats mainly algae, including corallines."
I saw one at Fish Gallery last week. The funny thing had all kinds of things stuck onto him. I think it was selling for ~25 dollars if I remember correctly.
They will pick up things and carry them around for days...Mine has been caught carrying snails, frags, my baby clam...He will also deposit them where hes sees fit. Lost a few frags because of him. DNA usually has them.