'1 wonder if you can help solve a conundrum for us in our garden?' asks a Hampshire reader. 'On one special gravel path a number of little heaps of gravel have appeared and the ground round each heap is quite smooth and hard. There is, I believe, a tiny hole in the ground below the heap and generally a small stick stuck in the top. These heaps appeared on one short path, but they are now spreading all over our gravel paths round the house and we cannot find out the cause. It seems to be done after dark as we never see any movement and if this was any kind of worm we cannot understand how it could collect all the loose gravel round the heap, leaving the path bare of loose gravel round each heap. That must have been done outside each heap and I can't see how a worm could have done it. No one here seems to have ever seen it before. It is quite mysterious. Now there are hundreds over all our paths—they are spreading everywhere. We have not raked them down Yet as we want to find the reason. I can count fifty or sixty heaps on one short path. Our soil here is good for about a foot and then clay and we never double-dig the garden. As we have lived here for twenty years and came when the house was first built, it all makes it more mysterious!'