IF you grope about in the dark nooks and corners of a rock-pool, quite close down to the water’s edge, when the tide is out, you may perhaps find a curious little creature which looks rather like a greyish-white cucumber, with an odd feathery tuft at one end of its body. This is a Sea Cucumber, or Sea Gherkin, and is chiefly remarkable because it seems to suffer very much at times from eating something which does not agree with it. Then it cures itself in a very odd way indeed. It gets rid of almost all the inside of its body, reducing itself to very little more than an empty bag of skin, with just a little tuft at one end! It throws off its teeth, it throws off the lining of its throat, it throws off all its digestive organs. You would think that it would kill itself by doing this, wouldn’t you? But it does not. And before very long new teeth, a new throat lining, and new digestive organs grow in the place of the old ones, so that in a few weeks’ time the animal is just as perfect as it was before!