Wasn't sure about this when I saw it but it's growing on me. It looks like a spherical swirl that sits on a cushion of some sort of frit or bubbles. The top half of the sphere is larger than the bottom half. Difficult to be sure what I am calling frit actually is - some of it is bubbles but some almost looks like dust sized particles maybe of mica. There are silvery reflections but that could just be light catching the bubbles. Weighs 640g and measures 3ins wide x 3ins high. The base is polished flat and does have signs of age wear. Any thoughts as to an ID would be appreciated. I'll add a second lot of pictures. Some pictures are against a black background as that seems to give a better idea of the colours.
Many thanks
Alastair