Evolution of the first example galaxy from Fig. 1. The shells develop after a massive radial merger event, which also causes the value of λ_Re to sharply drop and converts the galaxy into a slow rotator (where λ_Re is measured from the edge-on projection). Top: mock images of the stellar component from a projection in which the shells are especially clearly visible. The red lines trace the orbit of the infalling galaxy until the respective point in time. Middle: velocity maps. The circles indicate the ellipses at one and three half-mass radii. Bottom: velocity dispersion maps.