Colours and markings vary between crystals. You are purchasing the Septarian Crystal Lingam, pictured.
About Septarian Crystal Linghams (Lingam)
Septarian crystals, also known as Dragon Stone, formed 60 million years ago. The distinctive patterns found on Septarian crystals are due to Calcite (the yellow centres) and Aragonite (the brown borders) which formed as a result of organic matter from the ocean being covered in sediment, forming mud balls. As the ocean disappeared, these mud balls dried out and the Calcite minerals from the organic matter filled the cracks, forming the yellow centres.
Septarians are great crystals to use for public speaking as they will give you confidence and clarity. It is also said that Septarians can improve the immune system, skin disorders, kidneys and blood.