Luminosity-weighted mean stellar age versus the logarithm of the sSFR for both galaxy samples (normal SF and EELGs), colour coded according to the different galaxy family (left panel) and according to the logarithm of sum of all the most prominent emission line fluxes (middle panel, units of 10⁻¹⁶ erg cm⁻² s). The right panel illustrates the inter-connectivity of these three physical properties in a 3D parameter space, additionally displaying the resulting 3D surface that was fitted to the data.