In some ways these curious creatures are very much like sea anemones, and if you were to find one with its tentacles spread you would be almost sure to think that it was a small anemone. But if you touched it you would find that you had made a mistake, for instead of closing itself up into an almost shapeless lump of jelly, as the anemones do, it would just draw back its tentacles, and leave a kind of flinty skeleton still standing up. For madrepores are really much more like the wonderful little creatures which make coral. They suck lime, in some strange manner which nobody quite understands, out of the sea-water, and build it up round and underneath their own bodies. And if you startle them in any way they draw themselves down inside this shelly covering, and disappear from sight altogether; so that all that you can see is a number of thin plates standing upright on their edges, and looking rather like the lower surface of a mushroom turned into stone. Madrepores feed on very tiny animals, such as the fry of small fishes, and the zoeas of shrimps and prawns. And they catch their victims by means of a number of fleshy tentacles, which are very much like those of the sea anemones, except that they always have little round knobs at the tips. These tentacles are set with numbers of tiny cells containing slender poisoned darts, just as those of the anemones are. If you want to find madrepores, you must look for them among the rocks near the water’s edge when the tide is at its lowest. But they are not very common, and on many parts of the coast they are never found at all. PLATE XLIII THE SEA FINGER (2) If you walk along the shore as the tide goes out, you may often find a soft, pink, fleshy object which has been thrown up by the waves. And if you search among the pools at low-water, you are nearly sure to see other soft, pink, fleshy objects just like it growing upon their rocky sides, or upon the stones and shells which lie at the bottom. They are often known as “dead men’s fingers,” or “dead men’s toes.” But as those are not very nice names, we will call these objects “sea fingers.” Now if you pick up one of these sea fingers and look at it carefully, you will see that its surface is pierced all over with numbers of tiny holes. And if you take a good strong magnifying-glass, and look at one of the holes through that, you will see that it is shaped like a little flower with eight petals, or a star with eight rays.