Distribution of the galaxies of the z355 over-density in the RA-Dec plain. The galaxies are separated in three group with the kernel density estimation, as explained in the text and colour coded accordingly: group A (yellow) at RA ∼53.08, group B (red) at RA ∼53.12, and group C (purple) at RA ∼53.15. The symbols follow the same scheme as in Fig. 5. We also show two passive galaxies from the literature as green crosses.