Abstract: A corner piece for forming a corner of a container, with a hold which can be grabbed by external gripping device, stacking elements in the shape of a solid protrusion and coupling elements which can be activated and deactivated and which includes a movable coupling element which can be moved between an activated position and a deactivated position, as well as an activator mechanism for activating and deactivating the coupling elements, which activator mechanism can be coupled to external driving elements.