The music of the spheres: Transition-metal phosphate colloidal spheres with one metal (Mn, Fe, Co, Ni, and Cu; see picture) or more than one metal (such as Fe-Ni, Co-Cu, Fe-Co-Cu, Fe-Co-Ni-Cu, Mn-Fe-Co-Ni-Cu, and Mn-Fe-Co-Ni-Cu-Zn) were synthesized in solution at low temperature. Porous and hollow iron phosphate spheres were prepared by adjusting the pH value of the reaction.