Septarian nodules are a type of concretion with cracks that become filled with minerals, in this case, calcite.
In sedimentology and geology, a nodule is small, irregularly rounded knot, mass, or lump of a mineral or mineral aggregate that typically has a contrasting composition, such as a pyrite nodule in coal, a chert nodule in limestone, or a phosphorite nodule in marine shale, from the enclosing sediment or sedimentary rock. Normally, a nodule has a warty or knobby surface and exists as a discrete mass within the host strata. In general, they lack any internal structure except for the preserved remnants of original bedding or fossils. Nodules are closely related to concretions and sometimes these terms are used interchangeably. Minerals that typically form nodules include calcite, chert, apatite (phosphorite), anhydrite, and pyrite
Imaged using a canon 5DS R and Stackshot 3x with turntable to provide 108 images which were then processed using agisoft photoscan at high levels.
This object is scanned by Fossils in Shropshire