'Madenstein' from Chemnitz-Altendorf. The 'Maden' (maggots) are in fact
leaflets of Pecopteris.
Photo R Rößler. Coll. Museum für Naturkunde, Chemnitz.
Polished surface of Hornstein (chert) from Chemnitz-Altendorf. Width
of the photo 4 cm.
The C-shaped structures are the remains of pinnules of Pecopteris.
The pinnules were very thick. This fact points at adaptation to dry or saline