reasonably well understood: though the details depends on the configuration of the flow, the route to fragmentation necessarily involves the formation of elongated liquid ligaments [*e.g.* @marmottant_2004a; @villermaux_2004; @villermaux_2007], which is the only geometry unstable against the Rayleigh-Plateau capillary instability leading to fragmentation into drops. Fragmentation must therefore be preceded by a change of topology of the metal phase, from a compact volume (the core of the impactor) toward metal ligaments. Ligaments can be produced either directly by hydrodynamic instabilities or turbulence, or indirectly by the bursting of metal sheets, the liquid from the sheets then collecting into ligaments [*e.g.* @villermaux_2007]. In the context of metal fragmentation in a magma ocean, laboratory experiments and numerical simulations suggest that the production of both metal ligaments and sheets can result from a combination of Rayleigh-Taylor and shear instabilities, turbulent fluctuations, and interactions with the shear related to the crater opening and the following flow [@deguen_2011; @deguen_2014; @kendall_2016; @landeau_2014; @wacheul_2014; @wacheul_2018]. Once formed, ligaments can fragment into drops as a result of the Rayleigh-Plateau capillary instability [@eggers_2008; @marmottant_2004a; @marmottant_2004]. Figure \[fig:sed\] illustrates the fragmentation sequence just described, which is to be considered as generic: if fragmentation of planetesimal’s core indeed happens, it corresponds 