  We present new evidence supporting the quasi-unit cell description of the
$Al_{72}Ni_{20}Co_{8}$ decagonal quasicrystal which shows that the solid is
composed of repeating, overlapping decagonal cluster columns with broken
10-fold symmetry. We propose an atomic model which gives a significantly
improved fit to electron microscopy experiments compared to a previous proposal
by us and to alternative proposals with 10-fold symmetric clusters.
