Redshift distributions for each group in the z355 over-density. The top panel corresponds to group A, showcasing a peak at z ∼ 3.7; the middle panel to group B, with a peak at z ∼ 3.55; the bottom panel to group C, with a peak at z ∼ 3.75. The vertical lines indicate the redshifts of the passive galaxy we identified in group B and the passive galaxies from the literature hosted by group A and B.