The pictures show the front and back of a small slab of stone (approx 6in x 6in x 0.5in thick). I have no experience of fossils and so am completely in the dark with this. The stone was on the stony beach which was exposed due to low rainfall - it would ordinarily be under water in a small stream about 2m wide. The pattern is 3D - as if the dark areas within the lighter lattice-type lines have been slightly hollowed out (perhaps only by 0.5 mm). A friend guessed that they may be plant fragments. The stream runs close to an area in Scotland frequented by Druids many centuries ago, as well as being the site of a Roman marching camp (Circa 54-55BC). I wondered if the stone had been carved rather than imprinted or shaped by weathering. I'm afraid I'm not a photographer, but if on first sight the stone seems worthy of further inspection I have a friend who is a professional photographer and can easily have better images uploaded.
Also, can only upload the 'front' - which is the more interesting side, due to Mb limit. Once again, I can get my friend to cut the byte size and upload more images if this is of interest.
Kind regards, David