Crystallization of Coccolith Calcite at Different Life‐Cycle Phases Exhibits Distinct Degrees of Cellular Confinement

Coccolithophores are a group of unicellular marine algae that shape global geochemical cycles via the production calcium carbonate crystals. Interestingly, different life-cycle phases same coccolithophore species produce very calcitic scales, called coccoliths. In widely studied diploid phase, crystals have anisotropic and complex morphologies, while haploid cells coccoliths consisting solely calcite with simple rhombohedral morphology. Understanding how these two control crystallization is highly sought-after goal, yet, phase has rarely been studied, process by which they form unknown. Herein, advanced electron microscopy employed to elucidate cellular architecture calcification in cells. The results show contrast diploid-phase calcification, coccolith-forming vesicle haploid-phase voluminous. this solution-like environment, nucleate grow asynchronously resembles growth bulk solution, leading morphologies distinct mineralization regimes suggest architecture, specifically confinement process, pivotal determinant biomineral morphology assembly.