Septarian BowlCrystal Meanings: Septarian nodules are unique in that they were formed as a result of volcanic eruptions and attracted dead sea life chemically bonding them to the sediment and forming mud balls. They are composed of Calcite, which makes up the yellow centers, Aragonite which are the brown lines, and outer grey rock, which is Limestone. The name Septarian comes from the Latin word "septum" meaning seven, which means a wall or enclosure. Septarian is