What is it about?

Modern scleractinian coral species, including those forming coral reefs, were thought to produce skeletons exclusively of one variety of calcium carbonate - aragonite. We described asymbiotic Paraconotrochus antarcticus from the Southern Ocean that is first example of an extant scleractinian that forms a two-component carbonate skeleton, with an inner structure made of high-Mg calcite and an outer structure composed of aragonite.

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Why is it important?

Bi-mineralic skeletal composition of this coral skeleton supports interpretation that the biomineralization process in scleractinian corals is strongly modulated by physiology of the animal. This is challanging for traditional purely physicochemical model of skeleton formation.


Discovery of pristine, calcitic-aragonitic scleractinian coral skeleton changes the basis for theories about scleractinian coral evolution through geological time, by removing the obstacle that skeletal mineralogy defines an impassable boundary between higher level anthozoan taxonomic units such as rugose (thought to be calcitic) and scleractinian corals (thus far considered entirely aragonitic). Furthermore, the discovery suggests that the unique geographic isolation of the Southern Ocean may harbor other organisms with preserved ancient traits.

Jarosław Stolarski
Institute of Paleobiology, Polish Academy of Sciences

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This page is a summary of: A modern scleractinian coral with a two-component calcite–aragonite skeleton, Proceedings of the National Academy of Sciences, December 2020, Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2013316117.
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