Galaxy distribution in NUM catalogue at z = 0. Top row: Panels a to d, colour-coded by H I mass, show the distribution for all galaxies (panel a), galaxies with with 0 < d_fil/h⁻¹ Mpc < 4 (panel b), 4 < d_fil/h⁻¹ Mpc < 8 (panel c), and 8 < d_fil/h⁻¹ Mpc < 12 (panel d), respectively. Panel e shows the H I mass distribution for galaxies with different distances to the filament that are measured within the same thin slice as in panels a–d; these are blue for all galaxies, cyan for 0 < d_fil/h⁻¹ Mpc < 4, green for 4 < d_fil/h⁻¹ Mpc < 8, and orange for 8 < d_fil/h⁻¹ Mpc < 12. The bottom row is the same as top row, but colour-coded by H₂ mass.