Neochetoceras steraspis with Aptychus.
Neochetoceras steraspis. The flanks are adorned with indistinct ribs and can sometimes even appear flat.
Also, a part called the Aptychus is sometimes found in Solnhofen, Germany. This is thought to be either the ammonite's jaw apparatus or a lid for the living chamber.
I was looking for an ammonite with the aptychus preserved at the end of the living chamber (I often see specimens where the aptychus is completely detached or in the middle of the phragmocone, but finding one at the edge of the living chamber was difficult).
Purchased at the "31st Tokyo International Mineral Fair" in Shinjuku from the booth of Krautworst Naturstein GmbH, a German fossil shop famous for Solnhofen fossils. The price tag was 4,500 JPY, but they gave it to me for 4,000 JPY.
