"You'll be calling a sponge a plant next. See those red lumps, near the
bottom of that rock? Those are sponges."

"Now there's some real coral!" the boy cried.

"All coral is real coral. What you are looking at is probably a form of
the stag's horn variety," the curator said, "and that does look more
like the coral of commerce. But everything you are looking at, nearly,
is coral. These great dome-like stones, do you see them?"

"The ones that look like the pictures of a brain?"

"Yes, those are called brain-stone or brain-coral. And those others,
just the same shape only with little holes, instead of grooves, that's
star coral."

"Then there seem to be some that look like a bouquet of flowers all
stuck together."

"That's rose coral," was the reply, "and those are the three forms you
see more generally."

"But where's the pink and red coral? If it's as easy to get at coral as
this, I don't see why people don't come here and make a fortune."

"Fortunes aren't quite as easy to pick up as that. This coral has no
market value; the variety that is used for jewelry comes mainly from
Japan and from the Mediterranean, and the governments of the various
countries keep it under constant watch."

"That's why. I see now. Oh!" exclaimed the boy as some fish swam under
the glass suddenly. "Just look at those angel-fish. They seem twice as
brilliant as the ones I saw in Devil's Hole."

"Of course," the curator said, "you would expect them to look dull in
dull surroundings. That is color protection. Here, everything is gaily
colored and striped and streaked and dotted, so the fish are, too. That
helps them to hide and be unnoticed. A plain-colored open sea fish could
be easily seen."

"Look, sah," said Early Bird, turning to the boy, "Ah've got a little
sailoh's choice, Ah caught this morning; Ah'll throw him in and yo' can
notice how plain yo' can see him."

He tossed the fish overboard. The silver scales shone and gleamed
brilliantly in the transparent water but Colin had barely time to notice
what a conspicuous object it was when in a swirl of water a score of
small fish of all sorts surrounded the morsel. But the groupers followed
hotfoot and the little fish fled. Then came retribution, for, from a
crevice in a near-by rock, out shot the eel-like form of a green moray
and disposed of one of the groupers in short order.

"Did I tell you about the moray?" Colin asked, and on receiving a reply
in the negative, he recou