The Devil's Toenails

Like all men, when the Devil cut his toenails he left them all over the place, probably much to the fury of his wife, Lileth, who was expected to hoover them up. One of the places he dropped them - and it must have been a favourite place for him to cut his toenails because there are loads of them there - was Mingary Castle, to the east of Kilchoan.

The Devil's toenails can be found in a series of stepped rocks just below the high-tide mark immediately to the east of the castle. Since the rock is Jurassic in age, these are the remains of nails he clipped at least 150 million years ago, so it isn't surprising that they are welded into the rock.

The best examples of Devil's toenails come from Liassic rocks in England, from places like Redcar in North Yorkshire or the Gloucestershire Cotswolds, where this unusual fossil was given its very appropriate name. Scientifically, its genus is Gryphaea and the species at Kilchoan is likely to be arcuata.

The Gryphaea family was highly successful during the Jurassic and Cretaceous. It was a bivalve, but a very unusual bivalve. Most bivalves, as their name suggests, have two equal-sized shells: cockles, common on the mudflats around Kilchoan Bay, are a good example. In its evolution Gryphaea did the same as its close relatives, the oysters: it lay on its side on one shell, making it larger and the other shell smaller, so it acted as a lid. But, while the oyster family stuck the bigger shell to something solid like a rock, Gryphaea lived on the sea bottom, on soft mud, using its bigger shell like a boat so it floated on the mud. In this position it filtered water for food.

Floating on mud may seem a precarious existence, but Gryphaea must have been very good at it as, in those places where it is found, it is often present in hundreds, so it is a common and well-known fossil. Yet, mysteriously, we don't find any in the rocks after the end of the Cretaceous, about 60 million years ago. I suppose the only person who knows why is Lileth.

Photo of Gryphaea courtesy Dlloyd at Wikipedia, link here.