Left: around 160 Myr after the big bang, three small galaxies merge in the simulation. Each progenitor enters with its own stars, with colors labeled in the right panel, and the merged galaxy continues to form stars. Right: we show the birth time and metallicity of each star in this system; the galaxies formed stars at slightly different metallicities prior to merging. Each star is colored by its galaxy of origin. We investigate more chemical abundances in Figure 6 to show that structure in chemical abundance space can correspond to the origins of the stars.