The Folklore of Aptyxiella portlandicas 

Taken from : 

" 'Formed Stones', Folklore and Fossils."  Michael G. Bassett. 

Screwstones and St. Cuthbert's Beads

Two quite different and unrelated groups of fossils are referred to colloquially in Britain as Screwstones.  In some parts of southern England the term is used for a number of spirally coiled univalved molluscs known as gastropods, of which the modern whelk is a good living example.  In the fossil state the resemblance of these shells to a screw thread becomes even more pronounced when the shell material itself has been destroyed after the infilling of the interior with sediment to form a natural mould.  The best known screwstones are from Jurassic rocks, notably the Great Oolite around Bath and the Portland Stone of Dorset, both of which are used extensively as building stone.  On the Isle of Portland many gastropods occur throughout the succession, but the quarrymen reserve the term screwstone almost exclusively for the moulds of a single species from the Portland Stone known as Aptyxiella portlandica.  The abundance of this species and is familiarity to quarrymen and geologists alike have led to its becoming known as the Portland Screw.

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From Staffordshire Plot described similar specimens as screwstones, but he failed to realise that they represented the axial infillings of other 'formed stones', for he differentiated them from unaltered crinoid stems which he described as 'Entrochi or wheels within wheels'.  In the same passage he referred to individual columnals from the stems which had long been used as beads, often strung together to form a necklace or rosary; in many parts of the country these are known as St. Cuthbert's beads, named after the same St. Cuthbert of northern England who is associated with the legend of the Whitby snakestones.  St. Cuthbert's monastic retreat is generally supposed to have been on the island of Lindisfarne [Holy Island] off the coast of Northumberland, and it is from that island that the legend of the threading crinoid columnals as a rosary is best known, particularly in the following passage from Sir Walter Scott's Marmion:

But fain Saint Hilda's nuns would learn

If, on a rock by Lindisfarne,

Saint Cuthbert sits, and toils to frame

The sea-born beads that bear his name.

A small islet on the south side of Lindisfarne, connected to the main island at low tide and known locally as St. Cuthbert's Isle, may have been the true location of the cell.  It is interesting that shales between Lindisfarne and St. Cutherbert's Isle yield abundant crinoid stems that often weather our freely from the rock, and would therefore have been much more readily collected than specimens from the massive crinoidal limestone of the main island itself.

In some other parts of England, rounded crinoid columnals were once referred to as fairy money, while in Germany they were named similarly as St. Boniface's pennies (Bonifacius Pfennige). 

Taken from : 

" 'Formed Stones', Folklore and Fossils."  Michael G. Bassett.  Department of Geology, National Museum of Wales, Cardiff.  Geological Series No. 1.  Cardiff, October 1982. 

© National Museum of Wales 1982.