OCEAN ANIMALS: SPONGES, SEA-ANEMONES, ETC. 129 



or made into ornaments. But in tropical oceans there 

 are whole islands of coral (figs. 90, 91), or long coral reefs 



Fig. 90. — Coral islands, Nukulai and Mokaluwa, of the Fiji group. (After 

 photograph by W. C. Mc Wood worth.) 



(fig. 92) fi-inging the shores of continents, formed by the 

 skeletons of millions of polyps. For as they live closely 



Fig. 91. — Western part of Storm Island (Fijis), a coral island; the trees are 

 cocoanut palms. (After photograph by W. C. Mc Wood worth.) 



massed together in great colonies their skeletons form solid 

 stony banks. Coral islands have a great variety of form, 



