Detailed view of one representative filament at z = 0 in EAGLE (top) and TNG100 (bottom). From left to right, panels show maps of the gas density, temperature, pressure, and metallicity in a 16 × 16 × 1 Mpc slice aligned with the best-fit plane of the filament. White dotted lines trace the edges of each filament as identified from the dark matter. There is abundant structure within the filaments, both along and perpendicular to the spine, with clear differences between the two simulations (see text for details).