Grounded in symmetry -[ HMM ]-

A reflection of a NEMA 5-15P plug. I suspended the plug above a mirror tile to get this shot.

 

This plug, with its U-shaped ground (earth) prong, is of the replacement kind. Round ground pins are normally found on plugs of molded cord assemblies, including the now very common power cords with IEC 60320 receptacle ends.

Done