Intrinsic size (HWHM) as a function of absolute magnitude for all the clumps or single compact (isolated) sources identified in the MDLF. The points are color-coded according to their intrinsic magnitude (color bar on the right) and size-coded with the redshift value. The cloud of points in the top-left of the diagram represents non-lensed objects belonging to the GOODS-South field (see text). The insets show the color images of three examples with large magnification and possibly hosting extremely small objects, compatible with being single star clusters, such as the source dubbed “D1core” (EV19, Vanzella et al. 2019) or the star complex possibly hosting Pop III stellar population (EV20, Vanzella et al. 2020b). Images 1c and 12 are discussed in Sect. 6. From top-left to the bottom-right of the diagram, luminosity from −22 to −10 and sizes from kpc to a few parsec scale embrace galaxies, clumps, and star clusters. The error on M_UV depends on the magnification and photometric uncertainties, and is typically ≲0.5 mag for the lensed sources. The typical error on the HWHM also depends on magnification and, conservatively, it is within the 50% of the reported value.