Kenneth J. McNamara
Shepherds' crowns, fairy loaves and thunderstones; the mythology of fossil echinoids in England (in Myth and geology)
Geological Society Special Publications (2007), 273 279-294

Abstract:
The presence of fossil echinoids in archaeological sites in southern England that range from the Palaeolithic through the Neolithic, Bronze and Iron Ages, Romano-British to Anglo-Saxon indicates that humans have long had a propensity for collecting these fossils. The palaeoethnological significance of fossil echinoids can be determined from a number of criteria. The fossils may occur with the dead, either in burials or cremations, or be associated with past activities of the living. These include presence on a flint worked as a tool; artificial alteration of the fossil; association with human habitation; or occurrence outside the area of natural geological occurrence. Their archaeological association provides an indication that these fossils have been collected by people for hundreds of thousands of years and, at times, attained a high degree of spiritual significance. Moreover, recent folklore associated with them, particularly their folk names, such as shepherd's crowns, fairy loaves and thunderstones, provides a further insight into the myths that were associated with them. These indicate the use of fossil echinoids in both "Celtic" and Norse mythologies where they played a role in resurrection myths. The occurrence of fossil echinoids in a medieval church is indicative of retention of "pagan" belief systems in a Christian context.