A VERY beautiful kind of sea-anemone (common at Felixstowe) is the Daisy or Sagartia troglodytes, (Fig. 6, a), which has a very long body attached to a rock or stone far below the sandy floor of the pool, on the level of which it expands its thin, long, ray-like tentacles, coloured dark brown and white, and sometimes orange-yellow. As soon as you touch it it disappears into the sand, and is very difficult to dig out. The most beautifully coloured of all sea-anemones are the little Corynactids (half an inch across), which you may find dotted about like jewels, each composed of emerald, ruby, topaz, and creamy pink and lilac, on the under surface of slabs of rock at very low tide in the Channel Islands. One of the most puzzling facts in natural history is that these lovely little things live in the dark. No eye, even of fish or crab, has ever seen what you see when you turn over that stone. It is a simple demonstration of the truth of the poet Gray's statement, that many a gem of purest ray serene is concealed in the dark, unfathomed depths of ocean! A splendid anemone is the Weymouth Dianthus (see the frontispiece of this volume), so named because it is dredged up in Weymouth Bay. It is often six inches long, and has its very numerous, small tentacles arranged in lobes, or tufts, around the mouth. It is either of a uniform bright salmon-yellow colour or pure white. When kept in an aquarium it fixes itself by its disk on the glass wall, and often, as it slowly moves, allows pieces of the disk to become torn off and remain sticking to the glass. These detached pieces develop tentacles and a mouth, and grow to be small and ultimately full-sized Weymouth anemones.
If the disk were spread out and gave rise to little anemones without tearing--so that they remained in continuity with the parent--we should get a composite or compound animal, made up of many anemones, all connected at the base. This actually happens in a whole group of polyps resembling the sea-anemones. They grow into "stocks," "tree-like" or "encrusting" masses, consisting of hundreds and even thousands of individuals, each with its mouth and tentacles, but with their inner cavities and bases united. These are the "coral polyps," or "coral-insects" of old writers, of so many varied kinds. One further feature of great importance in a "coral" is the production of a hard deposit of calcite, or limestone, which is thrown down by the surface of the adhesive disk, and is also formed in deep, radiating "pockets," pushed in to the soft animal from the disk. The hard deposit of calcite is continuous throughout the "stock," or "tree," and when the soft sea-anemone-like animals die, the hard, white matter is left, and is called "coral." Very commonly this white coral shows star-like cups on its surface, which correspond to the lower ends or disks of the soft sea-anemone-like creatures which deposited the hard coral. In a less common group (represented commonly on our coast by the so-called "Dead men's fingers" found growing on the overhanging edges of low-tide rocks) the hard coral material does not form cups for the minute sea-anemones which secrete it, but takes the form of a supporting central or axial rod (sea-pens), or branched tree (sea-bushes), upon which the fleshy mass of polyps are tightly set. This is the case with the precious red and pink coral of the Mediterranean (which is now being "undersold" actually in the Mediterranean markets by a similar red coral from Japan, usually offered as the genuine article, which it is not!).