On the Externsteine Descent from the Cross relief, the bent structure in the right centre is popularly identified as Irminsul. Though this may be correct, it is not supported by any contemporary sources.
Detail (via Irminsäulen / Irminsul)
Sacred Marriage with Irminsul 3rd Century, Germany (via http://odinsvolk.ca/irminsul.htm)
Bronze Razor depicting Irminsul, 2nd Century BCE, Denmark (via http://odinsvolk.ca/irminsul.htm).