Can you help identify the engraving on this stone?

This object was found recently on the Little Thetford side of our Bronze Age causeway. According to Dr Robert Young, this calcareous rock has calcite crystals on the reverse side and is not from this area. The flatter face contains an elaborate engraving linked to what appears to be a funnel near the outer edge—middle-top in the image. Does this apparent funnel suggest that the artefact was part of a precious metal mold?

These flints were also found at the same time and place. The lighter coloured flint looks like this one.

Click any image for a larger version.

Engraved stone (reverse)

Flint spearhead (1)

Flint spearhead (2)

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