SEM images of aragonite and calcite grown in vitro and identification of polymorphism using XRD. (A) Crystals grown in aragonitic solution without any presence of OM; only aragonite crystals were grown. (B) An extended view of aragonite crystals, arrows indicate aggregation of aragonite. (C) Verification of aragonite crystals by XRD. (D) Crystals grown in aragonitic solution in presence of OM (containing 1.4 μg/mL proteins), 70% aragonitic and 30% calcitic crystals were formed. (E) An extended view of crystals. The red arrows and yellow circles indicate aragonite and calcite minerals, respectively. (F) XRD verification of experimental crystals formed demonstrating 70% aragonite and 30% calcite minerals (including the main band of Mg-calcite).