Short Spine Urchin

The rock boring urchin, scientifically known as Echinometra lucunter, is a marine echinoderm native to the warm intertidal reefs of the Caribbean, Gulf of Mexico, and tropical Atlantic. Reaching an average test (body) size of 2 to 3 inches (5 to 8 centimeters) with stout, medium-length spines extending outward, it typically displays a dark reddish-brown, dull purple, or black coloration. These urchins are named for their unique ability to erode limestone and coral rock. Using a combination of their sharp teeth a five-jawed apparatus known as Aristotle's lantern and the abrasive grinding motion of their spines, they bore deep burrows directly into live rock and reef structures to create protective crevices against strong wave surge and predators. While wedged inside these hollows, they extend their spines and tube feet to trap passing drift algae, macroalgae, and organic detritus.

In a home aquarium, Echinometra lucunter serves as a hardy algae controller, scraping stubborn film, turf, and hair algae off live rock and glass. However, because of their natural bioeroding behavior, they require sturdy rock formations that are securely stacked, as their continuous grinding and burrowing over time can slowly weaken loose rockwork or loosen coral frags.