We investigate the factors that control the nucleation and growth of important calcium biominerals such as calcium carbonate, calcium oxalate, and calcium phosphate. We establish that macromolecules (nonionic polymers, polyelectrolytes, polypeptides, surfactants) can control the final morphology and polymorph by i) face-selective adsorption on crystals (thermodynamic regime) or by ii) temporarily stabilizing the primary nanoparticles formed thus leading to mesoscale crystallization (kinetic regime).