Septarian Dragon Eggs, also known as Septarian nodules, were formed around 50 to 70 million years ago as a result of volcanic eruptions. Dead sea life was chemically attracted to the sediment around it forming mud balls which, when the ocean receded, dried up.
Due to their bentonite content they also shrank in size, creating the cracks inside.
Septarian concretions or septarian nodules, are concretions containing angular cavities or cracks, called “septaria”. The word comes from the Latin word septum; “partition”, and refers to the cracks/separations in this kind of rock. It is filled in with minerals such as calcite (yellow) and aragonite (brown) causing the very unique patterns.
The mud balls tended to crack in 7 points in every direction, creating the distinct pattern these nodules exhibit.