Hot luminous stars show a variety of phenomena at their photosphere and in their winds which still lack a clear physical interpretation at this time. Among these phenomena are photospheric turbulence, spectral line variability (DACs and LPVs; see Sect. \ref{comparison}), wind clumping, variable or constant non-thermal X-ray and radio emission, chemical composition anomalies, and intrinsic slow rotation. In the previous section, we argued that the iron convection zone could be responsible for various of these phenomena.