Offset between metallicity of given stellar population and metallicity predicted by bulge MZ_*R for corresponding bulge mass as [Fe/H]−[Fe/H]_MZ∗R. We considered accreted (purple), disk-born (gold), and bulge-born (orange) stellar populations. Left panel: Metallicity offset as a function of the stellar mass of the bulge. Right panel: Median age of the stellar population itself. The lines correspond to the density contours at 20%, 40%, 60%, and 80% of each distribution.