Spurious fragmentation in filaments Starting from 64^3 grid pre-initial data. Starting from 64^3 Poisson pre-initial data. Starting from 64^3 grid + 64^3 small Poisson perturbation. Starting from 64^3 Poisson pre-initial data, but with the long-range force only. Obviously, this is unphysical but note that the regular fragmentation has disappeared.