Habitat: Limestone reef rock, often in the surf zone. Distribution: North Carolina thoughout to Brazil, Panama Caribbean. Natural History Notes: The urchin is resistant to physical stress (e.g. increased temperature and salinity) and is common in exposed, shallow reef habitats. Its burrowing ability makes it a significant factor in bioerosion of coral reefs. The urchin usually feeds from its burrow, generally at night, primarily on drift algae. Its predators include birds, conchs, and fish. The species is potentially useful as a bioindicator, as individuals have been shown to accumulate certain heavy metals in the gonads, test, spines, and lantern, reflecting degree of exposure to enivronmental pollutants. Depth: 0-45m Characteristics: This urchin reaches a maximum diameter of 150mm. The spines are generally blackish, although some specimens are reddish dorsally.