Bactrites aciculum cephalopod from the Mahantago Formation

Amongst the fossilized debris of the Mahantango seafloor I spotted a Bactrites aciculum cephalopod.The rock that it's on is a little fragile but the specimen is a good example of the species from the Mahantango formation.

Bactrites are identified by the lack of any septa (of even divided chambers), narrow body and the linear feature down the middle (which I believe is a compression fracture).

This specimens was collected from the Mahantango formation at Seven Stars, PA. The Mahantango is middle Devonian in age (Givetian stage) and I believe the locality exposes rocks that are equivalent to the upper Windom shale.