Besides these branching corals which resemble trees and shrubs, some grow in solid masses without sending off branches. Others assume the shape of graceful vases; all of these are gayly decked with star-like polyps of varied colors. Does it not seem to you as if the ocean was one vast store-house of beautiful things?
Fig. 2.—Mushroom Coral.
The mushroom coral (Fig. 2) looks indeed like a large mushroom, although you will notice that the leaflets are on the upper surface instead of being underneath, as they are in the vegetable mushroom. This coral is the skeleton of one huge polyp, and we see the depression in the centre corresponding to the little cups on most other corals.
Fig. 3—Organ-pipe Coral.
The organ-pipe coral consists of lovely crimson tubes standing upright, and connected at short distances by thin flat plates, which give it the appearance of being several stories in height. These plates may be distinctly seen in Fig. 3. When alive, a little polyp protrudes from the top of each tube, and being of a bright purple color, it makes a striking contrast with the crimson tube.
Fig. 4.—Fragment of Red Coral with Polyps.
Red coral, which is used for jewelry, grows in a bushy form on rocks at the bottom of the Mediterranean and Red Seas. The fleshy mass of this coral is colored red by the numerous red spicules it contains, while the polyps are pure white. The whole resembles a pretty red shrub spotted over with sparkling white flowers. The spicules in the centre of the branches form a solid stem, which takes a fine polish. Underneath the flesh the surface of the coral is marked with deep grooves, which are canals for the circulation of water. These grooves are shown at both ends of the branch in Fig. 4. They are always removed in polishing.