The morphology of calcium carbonate can be tuned by using aqueous double-hydrophilic block copolymer (DHBC)-surfactant mixtures in a chemical synthesis. Calcite hollow spheres (see Figure) and vaterite discs were obtained at different concentrations of sodium dodecylsulfate (SDS) in a DHBC-SDS system. In contrast, pine-cone shaped particles were obtained by using a DHBC-cetyltrimethyl-ammonium bromide (CTAB) system.