These brachiopods, called Calcirhynchia, are often found clustered together in ‘nests’. It’s quite common to find groups of shells like this. Modern mussel shells, which are not related to brachiopods, are often found in colonies attached to harbour walls, piers and larger rocks on the foreshore. As brachiopods also require a hard surface to attach to, it’s not surprising that they are found in clusters. They may have even been attaching to each other.
Find out more on the brachiopods page.