Goniatites americanus
Nautiloid
Upper Mississippian (Middle Chesterian)
Delaware Creek Member, Caney Shale Formation
Clarita, Coal County, Oklahoma, USA

17mm on 64mm matrix.

Cephalopod.

Goniatites is a genus of extinct nautiloid known from the Late Devonian to Late Triassic of North America, Europe, Asia, and north Africa. It lends it name to the Family Goniatitidae and to the more general tern, “goniatite,” which can refer to Paleozoic cephalopods in general.

Here’s a nice little nautiloid embedded in matrix. You can see the suture pattern in the shell.