Cabinet of Curiosities

Shelling Out

The bivalve Great Scallop (Pecten maximus)

The great scallop (Pecten maximus) is a bivalve, a marine mollusc possessing two shells. The 18th century Swedish scientist Carl Linnaeus is regarded as the father of taxonomy, the academic discipline whose focus is the classification and naming of organisms. His binomial system consists of two parts, the first or generic name which describes the genus or family to which a living organism belongs, coupled with a second, specific one. Scientific names are an engaging study in themselves. Pecten derives from the Latin ‘pectere’ meaning a ‘comb’ and relates to the similarity in shape to a stylish form of that implement, while ‘maximus’ means ‘largest’. It is commonplace to see the convex lower shell used as ashtrays and is familiar worldwide as the logo of the Shell Oil Company.

Pilgrim keepsake – the lower, convex valve

The shell is also a symbol very much associated with St. James the Apostle and his final resting place at Santiago De Compostella in Galicia, Spain. One of the most venerated religious sites in the world, pilgrims have flocked there since Medieval times. Returning devotees wore a scallop fixed to their hats or clothing to indicate that they had visited the site and it remained a cherished keepsake. An efficient vessel for scooping up water to drink, its radiating ribs symbolised the numerous pilgrim routes crossing Europe and converging at Santiago De Compostella. In 1996 the site of an Augustinian monastery and burial ground in the town of Mullingar was excavated by archaeologists. Burials were unearthed dating to the 14th century, some of which contained scallop shells indicating that their owners had made the arduous journey. A bronze statue was commissioned by the town to commemorate the Millennium in 2000. Called ‘The Pilgrims’, it features two Augustinian monks one of whom wears a scallop and links the modern town to its Medieval origins.

The ‘scallops’ served in seafood restaurants are the bivalves’ adductor muscle, by the alternate contracting and relaxing of which the shells are opened and closed. This action squeezes out water around the hinge at the back, the force of which propels the bivalve forward.

A neat circular perforation is noticeable near the centre of the fossil pecten shell. This is known as a predatory borehole and was drilled by some ancient form of whelk around 50 million years ago in the Eocene Epoch. Once the prey had been located, it drilled through the victims’ shell using its tooth-lined radula. As soon as the hole had been completed, the whelk secreted an enzyme into the scallop which immediately began to digest the flesh which it then consumed. A stony, still-life study of life and death in our distant past.

50 million year old predatory borehole

Echinoderms are a group of spiny skinned marine animals which display a five-fold radial symmetry. They include starfish, sea urchins, sea-lilies and brittle-stars. The skeletons of these animals are composed of the mineral calcite and as a result their ancient ancestors are commonly preserved as fossils. The sea-lilies are also known as crinoids, from the Greek ‘krinon’ and ‘eidos’ meaning ‘lily’ and ‘form’ respectively and stems, no pun intended, from their superficial resemblance to flowers. An extensive family, over 6,000 fossil species have so far been identified.

Fossil sea-lilies – Pentacrinites

Fixed on the end of a long stalk by which it was attached to the seabed, the body had arms equipped with fine feathery filaments that directed tiny food particles towards the mouth. The crinoids consisted of numerous conjoined disc-shaped segments which formed the hard structure of the animal. A small number of related species are still found in the depths of the world’s oceans. Working on an expedition to the Sahara Desert in Morocco some years ago I came across some fine crinoid fossils of a species called Pentacrinites. They are around 400 million years old and clearly display the feathery filaments on the arms.

Detail of Pentacrinites



© Vincent Butler Heritage 2020