The crystallization of CaCO3 in the presence of monolayer-protected gold nanoparticles is investigated here. It is found that crystals of CaCO3 grow around the gold nanoparticles, which act as nucleation templates, resulting in metal-organic-inorganic hybrid materials (see Figure). Control of the shape (spherical or needle-like) and polymorph (vaterite or aragonite) is also demonstrated.