Loop-like magnetic field structure (blue and red field lines) created by a convective flow (yellow arrows show the ascending parts of the flow, while the transparent grey scale shows the cellular pattern at the solar surface). The magnetic field lines are coloured according to the vertical velocity: red indicates upflow, blue indicates downflow. The “legs” of the magnetic field structure are created by stretching of the magnetic field lines by the downflows, while the loop top is carried up to the surface by ascending, warm convective flows. The simulation was performed with the Stagger code.