This chapter reveals parallels between the human ear and the fly ear (1) at the organ level in terms of tissue architecture, (2) at the tissue level in terms of development, (3) at the cellular level in terms of mechanosensory transduction, and (4) at the genetic level in terms of area-code specification and cell-type licensing. It also delves into the genetic pathways by which cells orient themselves within epithelia. Virtually all animals rely on the same two planar cell polarity (PCP) pathways to inform cells about the axes of the organs wherein they reside. The more familiar one is the core PCP circuit with 6 proteins, but there is another (non-core) circuit that uses 3 other proteins. One mystery that is explored here concerns an enigmatic line of symmetry in the utricle of the human inner ear. That line bisects the lawn of sensory hairs in the macula but its origin and function are unclear. To try to make sense of it, a similar line of symmetry in the fly eye is analyzed as a case study. Another (more opaque) mystery concerns how genomes establish area codes in epithelia in general. For that excursion a different case study is used (the fly's achaete-scute complex).