Among the originally aragonitic biota, only nautilids and ammonites have retained relics of pristine skeletons.
Katarzyna Janiszewska, Maciej Mazur, Marcin Machalski, Jarosław Stolarski 2018, 'From pristine aragonite to blocky calcite: Exceptional preservation and diagenesisof cephalopod nacre in porous Cretaceous limestones.', PLoS ONEhttp://europepmc.org/articles/PMC6300390?pdf=render. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
The cement-forming component come from the dissolved of aragonitic shells.
Bona Artazos, M. E., Acero Salazar, P., Mandado Collado, J., Torrijo Echarri, F. J. 2001, 'Modelizacion genetica de concreciones carbonatadas: aplicación al Devonico deTabuenca (Cordillera Iberica, España)', Estudios Geologicoshttp://estudiosgeol.revistas.csic.es/index.php/estudiosgeol/article/view/131/127. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)