Wikipedia
Lytocrioceras
Lytocrioceras is an ancyloceratine ammonite from the Lower Cretaceous with a shell that resembles a safety pin. The shell begins as a loosely wound spiral, followed by a straight shaft which makes a U-turn to go back is somewhat the opposite direction, ending in a jog, offset from the original coil.
Lytocrioceras was originally included in the Ancyloceratidae ( Lytoceratina), united with other similar forms but has since been reassigned to the Macroscaphitidae.