Darwin proposed that these organisms may accumulate into "fringing" or atoll like structures.
Purpling of tissue and exposure of bare skeleton are symptoms of infection of these organisms by Aspergillus sydowii, while stress induced decline of zooxanthellae density in these structures causes a decrease in their productivity and makes them turn colorless, a process which is called bleaching. Darwin proposed that these organisms may accumulate into "fringing" or atoll like structures. They are composed of calcium carbonate secreting anthozoa which form polyps. For 10 points, identify these organisms that sometimes form underwater structures such as the Great Barrier one off the coast of Australia.
Purpling of tissue and exposure of bare skeleton are symptoms of infection of these organisms by Aspergillus sydowii, while stress induced decline of zooxanthellae density in these structures causes a decrease in their productivity and makes them turn colorless, a process which is called bleaching.
{Coral reefs} [accept either]