Today I have a couple of Orthoconic cephalopod sections to show you. Both come from the island of Oland which lies off the eastern coast of Sweden near the town of Gillberga. Nearby, exposed in cliffs along the coast and a local quarry, are layers of limestone that are dated to the middle Ordovician (Darriwillian stage).
This is a section of an Orthoceras (possibly Endoceras)
This piece of conch belongs to a genera called Anthoceras vaginatum. It has a red coloration because part of the original shell is impregnated with Hematite.
I found this paper online that gives a description of the local stratigraphy of Oland and a field trip guide (useful for anyone who wants to visit).