h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

those little buggers are nasty. my brother fell into a pool of them at one point while tide pooling and had a bunch of little spines broken off in his foot, hands, arms and probably a few other places. When the spines snap off in skin they release a dye which turns the skin around the wound whatever color the urchin is . My brother got the ever-so-stylish purple colored urchin dye, thus speckling his extremities with little circles of a dark violet color. The spines stick around and were sore and couldn't be pulled out because the way they snapped meant the end of the spines were all below the surface of his skin. The cure for these things is apparently to soak the wounded body parts in vinegar, thereby disolving the spines. Hurts like hell, or so he claims, but it got rid of most of the spines and most of the color. He still has small specks of dark purple on his hands, though. The lesson here is to not walk on slippery rocks near shallow pools filled with sea urchins.