  By combining surprising new results from a full polarization analysis of
nodal angle-resolved photoemission data from pristine and modulation-free
Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ with structural information from LEED and
{\it ab initio} one-step photoemission simulations, we prove that the shadow
Fermi surface in these systems has structural origin, being due to orthorhombic
distortions from tetragonal symmetry present in both surface and bulk.
Consequently, one of the longest standing open issues in the fermiology of
these widely studied systems finally meets its resolution.
