The Atlantic Purple Sea Urchin (Arbacia punctulata) is native to the North Atlantic and found along the coasts of North America from Massachusetts, southward to the Yucatan Peninsula.
They can reach up to 8 cm in diameter. Its shell (test) is covered with tube feet used for mobility and camouflage. Five tooth-like plates on bottom of its test, called Aristotle’s lantern, are used for grazing on marine algae.