| Geopetal infillings in the internal cavity of the shells were observed and represented by poorly lithified micritic and aragonitic cement. |
| The Atlantic and Gulf Coastal Plains of the United States contain assemblages preserved as original aragonitic and calcitic material in unconsolidated sediments. |
| The mineralogic composition of carbonate platforms may be either calcitic or aragonitic. |
| The formerly aragonitic specimens are preserved as moulds and the calcitic faunal elements are usually partly decalcified. |
| Both specimens retain their original calcitic outer shell layer, original aragonitic middle and inner shell layers, and remnants of aragonitic ligament fibers. |
