Calcareous algae
Niihori, Hidaka city, Saitama pref., Japan
Early Cretaceous, Mesozoic (130 Ma)
Width: 10 mm. Calcareous algae in calcarious sandstone recovered from the Early Cretaceous (130 Ma) Takaoka Formation, the eastern end of the Sanchu Graben. White grains are Calcareous algae with characteristic mesh texture. The sedimentary environment of the Sanchu Graben is shallow marine.