Five-fold twinned structures are a class of important members in the family of metallic nanocrystals with face-centered cubic (fcc) structures, which can anisotropically grow into nanowires when their {100} facets are protected. In this communication, we first discover their unique growth mode that generates a new structure of palladium nanocrystals potentially enclosed by high-index facets, when the growth kinetics is manoeuvred.