Volume renderings of chromospheric density fluctuations (log ρ) at t = 11 360 s. All densities higher than log ρ = −3.6 and lower than log ρ = −9.6 are transparent. This means that the gray plasma is under-dense compared to the transparent plasma beneath it, and the blue plasma is over-dense compared to the transparent coronal plasma above and around it. The left two panels do not include magnetic flux rope field lines whereas the right two panels do, illustrating that an over-dense mini-filament in the chromosphere is aligned well with the non-reconnecting lines of the magnetic flux rope at that time. The magnetic field lines therefore act as a guide for identifying the mini-filament.