On this spot you will find a rock formation that is common between Pramollo and the Zollnersee lake bearing round inclusions similar to nuts, with dimensions that can reach those of an egg in rocks with a fine consistency. These are called concretions and are not fossils, but anorganic formations. Substances such as manganous and ferrous oxide are released in the rock and transferred due to the absence of oxygen. When oxygen is again present in sufficient quantity, these substances disappear and solid aggregates are formed, the concretions. Mineral precipitations, for example, are recognizable in the calcareous deposits in kettles.