Given the lack of any definite answers as to their formation and after a bit of soul searching I have removed 2 of these for analysis. A photo attached with a 1 cent coin for scale. I hope to get one cut in half and there is a possibility of dating if suitable.

Thanks Mikem, but they do not have a 'cauliflower' form, which I would associate with moon milk. Each pearl is roughly spherical but the outer surface is like a hedgehog with individual outward pointing crystal growths. I could see inwards for about 5mm between each growth point. To me crystal...

A couple of photos...

My first post here, I'm just after a trip into a cave in the beautiful Burren in County Clare where we found some amazing cave pearls that are covered in outward radiating calcite crystals. There are plenty of them occurring in a series of pools along a section of oxbow passage about 1m above...