Apologies for the late posting of the answer to last week’s mystery object, I lost all track of time over the Christmas break!

Last week I gave you this boring object to identify from the Dead Zoo:

Of course, by boring I mean it bores into materials, as it’s actually a pretty interesting type of mollusc, and by looking at the comments, it’s clear that everyone has a good idea of what it is.

I had hoped to trick a few people into thinking it could be a type of shipworm, by pointing out that this specimen has bored into pine, when this species much more commonly bores into softer rocks, like mudstones and chalk. They do this by using their muscular foot to attach themselves to the substrate and then they twist their shells into the surface.

The shell has multiple tiny rasping teeth all over the surface, which you can see on the specimen above, and this grinds away the rock (or in this case wood). You might expect the shell to be thick in order to achieve this, but actually it’s very thin – which is partly why the mollusc bores itself a hole in a hard substrate for protection.

This specimen is a type of Piddock and it was collected in Ireland, which can certainly help with the identification since there are only a few species of Piddock that have been found in Irish waters, although it does have a fairly characteristic feature readily visible – the beaked anterior end (which sits at the bottom of the bored hole, so this one is upside down).

This feature is seen in the Common Piddock, Pholas dactylus Linnaeus, 1758 while in species like the White Piddock and American Piddock the anterior end doesn’t form the same beaked shape. Well done to everyone who worked it out!

I did mention in the original post that it may not be very festive-looking, but the Common Piddock could be considered one of the most festive molluscs, since they bioluminesce, giving off a bluish green glow and an alternative common name for them is Angelwings due to the thin shell, shape and white colour. So not a boring boring mollusc by any means!