red-yellow maggot stone from the gravel pit at Nobitz near Altenburg, detail
Fig.3: Fern pinnules with empty sporangia in glass-clear chalcedony.
The wall structure of the cut
sporangia is distinctly seen from within. The slit for spore release is seen
on one of the
sporangia (centre left). coll. FROHBERG/Friedrichroda,
scale bar 0,50 mm