Line profiles and velocity bisectors for the Fe I transition at 868.6 nm. The filled circles in the upper panel correspond to solar observations. Solid lines are for 3D simulations and broken lines for 1D models. Note that the 1D calculation at solar-metallicity for this line (broken solid line) shows a non-zero velocity bisector, due to overlapping CN transitions included in all our calculations that distort the otherwise perfectly symmetric 1D profiles.