1860 4 82 All the animals that made these great reef-forming corals were confined, when alive, to the comparatively slight depth of fifteen fathoms.
1991 R. S. K. Barnes & K. H. Mann (ed. 2) x. 204/2 Endodermal cells of almost all of the reef-forming, or hermatypic, corals contain large numbers of symbiotic unicellular algae.