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an order of extinct foraminiferans that lived during the Carboniferous and Permian periods. The shell was very large, reaching 6 cm in length. It was lenticular, spherical, or fusiform. There were several imbricate whorls and chambers divided by septa. The wall of the shell was calcareous and consisted of one or two layers. Fusulinida were marine rock-forming organisms (fusulinid limestone). They are of great significance in the stratigraphy of Carboniferous and Permian deposits.