Heart-shaped lichens ( crustose ) , audubon corkscrew swamp sanctuary , florida

佛罗里达，auduboncorkscrew沼泽地保护区，心形地衣

Large numbers of grazing sea urchins reduced the abundance of crustose coralline algae , a species of algae that produce calcium carbonate , the basic building material of ocean reefs , researchers found .

研究人员发现，大规模放牧海胆可减少壳状珊瑚藻的分布量，由这种珊瑚藻产生的碳酸钙是海洋生物礁的基本组成物质。