I can't find any other than two to compare to though Sue, so they can't be that common? It's very similar design to one I found attributed as a Boffo penguin. It is quite a bit different to the labelled one I found from Phoenician, in terms of shape and also the way the wings are done. However I should imagine there are variations anyway, and I had queries about the speckly blue on the internal colouring wondering if it might have been a later Mdina piece or something initially. Mdina didn't create their blues like that did they? It's quite difficult to see the colour on the only one I can compare to, and how it is laid in or created.
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