Close-up view of the ejecta fingers and clumps emerging from the contact discontinuity, along with the perturbed magnetic field, in model W15-IIb-sh-MHD+dec-rl-hr at the age of Cas A. The irregular isosurface represents the ejecta, while the green volumetric rendering shows the shocked shell, as described in Fig. 1. The sampled magnetic field lines illustrate the magnetic field configuration, with colors indicating the magnetic field strength in units of µG (color bar at the bottom of the figure). The lower panel is the same as the upper panel, but with the isosurface removed to provide a clearer view of the complex magnetic field configuration. A navigable 3D graphic of the magnetic field configuration at the age of Cas A is available at https://skfb.ly/psYpK.