The Needle Sea Urchin (Diadema mexicanum) is a species of long-spined sea urchin in the family Diadematidae. It is native to the Pacific Ocean, primarily found along the coasts of Mexico, Central America, and parts of South America. Rounded body (test) covered in long, slender, needle-like spines that can reach up to 20–30 cm in length. Sharp and brittle, used for defense against predators. The spines may also inject venom that causes pain and irritation to humans or predators. Feeds primarily on algae, helping to maintain the balance of coral reef ecosystems by preventing algal overgrowth.