“Probably,” returned her mamma, “on some animalcules contained in the water, the forms of which are too minute to be visible to human eyes even though aided by powerful microscopes.”
“I can easily imagine they must be very small,” said Agnes, “as the creatures which feed upon them are so little themselves. But I think I have seen the pores in the coral.”
“I have no doubt you have,” said Mrs. Merton; “the pores in some of the kinds of sponge are also quite large enough to be visible to the naked eye.”
“But where is sponge found, mamma?” asked Agnes.
“It is generally collected from rocks in the sea,” replied Mrs. Merton, “about twenty or thirty feet deep, by divers, who in time become very expert in obtaining it. It grows so rapidly, that it is said rocks have been found covered with it that were completely cleared only two years before.”
“What kinds of coral are these mamma?” said Agnes, picking up two or three pieces which lay upon the stall.
Fig. 25.
Corals.
“I do not know the names of all of them,” said Mrs. Merton; “but I believe that kind which looks as though it were formed of small beads is called the chain coral, or Catenipora; and that other kind which appears covered with star-like flowers is called Aulopora.”
