DetailsNucula is genus of salt water bivalves which belong to the clam family, they are fairly small in size, even the modern day species, with these fossil specimens measuring around 1 to 1.5 cm in size. These are also the actual fossil shells themselves unlike the moulds which we also sell. These are of Carboniferous age, between 358 to 298 million years old. They were found in the Carboniferous shale in Blairskaith, Scotland, UK. The specimens will come supplied in a packet with a label.