Sea urchins (Echinoidea) are found along the Mediterranean and especially the Red Sea coasts of Israel. The most important species are Diadema setosum on the Red Sea coast, and Paracentrus lividus on the Mediterranean. When stepped on, the brittle spines penetrate and the venom they carry causes further damage. Thus the injuries are mainly mechanical, but may be complicated by a foreign body reaction to the bits of spine, to small detached segments of their covering epithelium, and damage by the epithelial venom. Severe pain, edema, local sensory loss and sometimes suppuration ensue.