National Geographic : 1934 Jun
MULTI-HUED MARVELS OF A CORAL REEF ( National Geographic Society FANTASTIC GORGONIANS ARE NOT PLANTS BUT ANIMAL COLONIES First cousins of the reef-forming corals are these sea fans (upper left), plumes (center), and bushes (lower left) of tropical sea gardens. Hanging from the lower side of the soft-spangled sea finger (lower right) are greenish extended polyps. Sometimes the polyps withdraw into the purplish stalk, leaving only their green tips protruding as in the upper and near sides. The building material of these polyps is not stone but a horny and flexible substance, so the Gorgonians sway to the rhythm of the ocean currents.