I'm rather fond of galls, as regular readers of this blog may have guessed! So here is another one I came across today in the woodland on a fallen leaf of pedunculate oak, Quercus robur. The smaller ones at the bottom of the leaf are the oak spangle gall, or Neuroterus quercusbaccarum, that featured here a few months ago, but what is the larger spherical one above them? Answer next week....