Black Sea Urchin

Although the black sea urchin has a pale-coloured body, it also has black spines, which is how it got its name. Interestingly, the black sea urchin appears to share a commensal symbiotic relationship with urchin-mouth worms, which are commonly seen around its mouth. With its threatening spines, the black sea urchin may provide a protected space for urchin-mouth worms to live in, at no benefit or cost to itself!