septarium
/sɛpˈtɛriəm/
noun
- A rounded rock nodule with internal cracks that have been filled with minerals, often forming a pattern like a turtle shell.
- Collectors prize a large septarium for its beautiful calcite and aragonite veins.
- The geology teacher showed the class a septarium that had been cut in half to reveal its inner pattern.
- This septarium was found in a clay deposit and later polished for display.