It looks like a leaf, about 30 cm long and 7 cm wide, in jurassic sandstone, north of Runswick Bay. I am delighted to say that the experts are still baffled by my previous find. I am going to have to do some serious reading on sedimentary geology and palaeontology not to be looking at things and classifying them as 'strange stuff in rocks'. I thought this one was a keeper, but the boulder looked about two tonnes in weight. I was hungry, so I left it.