The Ar+‐sputter‐induced ‘‘cone evolution’’ on Mo‐seeded Cu is known to entail the growth of hillocklike crystallites on the cone surface. Such crystallites have now been identified as Cu, by means of high‐resolution energy dispersive x‐ray analysis. The Cu crystallites grew selectively on the Mo lattice of seed layers, and sometimes at the seed‐layer apex which suffered from head‐on ion impact during sputtering. The crystallite growth was thus not a direct consequence of ion impact, leading to a hypothesis that a viscous overlayer of Cu on the growing Mo lattice condensed into dewdroplike crystallites upon switching off the ion beam.