Promicroceras planicosta (Sowerby)
Triangular piece of grey septarian limestone with a pair of dark 3d Ammonites on the top surface. Shows a slight resemblance to an Owl's head. 'Ammonite Marble' from Marston Magna.
Jurassic, Upper Sinemurian, Obtusum Zone, 'Ammonirte Marble'.
Marston Magna, Somerset.
Specimen : 5 x 4 x 3.3 cm.
