  Multiple space-borne cosmic ray detectors have detected line-like features in
the electron and positron spectra. Most recently, the DAMPE collaboration
reported the existence of such a feature at 1.4 TeV, sparking interest in a
potential dark matter origin. Such quasi-monochromatic features, virtually free
of any astrophysical background, could be explained by the annihilation of dark
matter particles in a nearby dark matter clump. Here, we explore the
consistency of producing such spectral features with dark matter annihilation
from the standpoint of dark matter substructure statistics, constraints from
anisotropy, and constraints from gamma-ray emission. We demonstrate that if
indeed a high-energy, line-like feature in the electron-positron spectrum
originates from dark matter annihilation in a nearby clump, a significant or
even dominant fraction of the dark matter in the Solar System likely stems from
the clump, with dramatic consequences for direct dark matter searches.
