Correlation between filament width, length, and central density (within 300 kpc from the spine) for EAGLE at z = 0. Top panel: Density vs. width coloured by length. Bottom panel: Length vs. width coloured by density. For both panels, points represent individual filaments, while black lines enclose the central 10%, 25%, 50% (thick), 75%, and 90% of points. There is a modest correlation between density and length, while length and width are largely independent apart from outliers with density ≳ 30× the cosmic mean.