Stromatoporoids refers to a marine life stromatoporoid that became extinct during the Mesozoic era. Stromatoporoids, together with corals, created reefs by assimilating carbon dioxide abundantly contained in sea water. This became the basis for limestone rocks. The exhibited specimen, from approximately 410 million years ago, is from Australia.
Carbon dioxide existed abundantly in earth's atmosphere and oceans. Limestone rocks stabilized carbon dioxide as rock.