"It really is coral, then?"
"As much as any island is. The base of any coral island is limestone, being made of the skeletons of coral polypi which have been broken and crushed by wind and weather and beaten into stone. Just as chalk is made of thousands of tiny shells, so coral limestone is made of myriads of coral skeletons."
"Why, that's like sandstone," cried Colin, in a disappointed tone. "I had an idea that coral was a sort of insect that lived in a shell and that colonies of these grew up from the bottom of the water like trees and when they died—millions of
them—they left the shells and these stone forests grew up and up until they reached the top of the water and then soil was formed and that was how coral islands began."
"I'm not surprised at your thinking that," his chief replied, "lots of people do. And though that theory is all wrong, still if it has given folks an idea of the beauty and wonder of the world, there's no great harm done. Plenty of people still talk about the coral 'insect.' It never occurs to them to call an anemone an 'insect,' but they don't know that the coral polyp is more like an anemone than anything else."
"But an anemone is a soft flabby thing that waves a lot of jelly-like fingers about in the water."
"So does coral," was the reply, "and it eats and lives just in the same way, only that the coral polyp has a stony skeleton and most of the sea anemones have not. But every different one has some sort of a story to tell and I believe they get joy out of life just as we do. Else why should some of these forms be so beautiful? You note them closely when we pass over some of the reefs, and I should judge we are coming to them now."
Certainly if the coloration was any clue, the boat
was coming to the great sea-gardens. Above the white bottom the water shone a vivid emeraldine green, changing to sharply marked browns over the shoals, while beyond the inner reefs it varied from all shades of sapphire blue to radiant aquamarine. Nowhere was the water of the same color for a hundred yards together, while every ruffling of the surface, every slant of sunlight gave it a new hue. Colin was entranced and wished to see more closely, but the boat was going too swiftly to let down a water glass and he was forced to wait a few minutes.
"Ah b'lieve, sah," said Early Bird presently, hauling in the sheet, "we might let the sail down heah. We'll drift just about fast enough fo' you to watch the bottom."