Last week I presented this mystery object for your identification delectation:

While this is such a heavily processed piece of skin, with most of the diagnostic features removed, an additional close-up image provided a clue:

People in the comments section and on Bluesky recognised that this is the skin of a member of the Batomorphi (AKA the Rays). While there were some differences in opinion on the species, there is one term that came up several times in several ways, but in the words of Chris Jarvis:

Much to my chagrin I think I might know what this is?

This is of course a reference to the material shagreen, which is a type of leather (often dyed green) with rough dentine inclusions that are polished to create “pearls” embedded throughout.

There are several species of Ray – and indeed some sharks – with skin used to make shagreen. One is called the Shagreen Ray, but I suspect that this is not an example of that species, despite it occurring in Ireland (there’s a very helpful guide to the Skates and Rays of Ireland if you’re interested).

I think this mystery object might be a Cowtail Stingray Pastinachus sephen (Forsskål, 1775), since that species has been extensively harvested to supply shagreen in the past, and the object is lacking the distinctive denticle patterns that can be used to help distinguish between the Shagreen Ray and other similar species.

It could of course be another species, and if anyone knows of a definitive set of features visible on this specimen, I would love to know what they are. So I would like to congratuate everyone who mentioned rays and shagreen!