Harry the cat was showing an inordinate amount of interest in some stones so I turned them over to look. It was a fascinating ants nest. I turned three stones and each had a nursery of different size eggs underneath - these, the next size down (which the ants rushed to carry to safety below ground) and absolutely tiny. Sadly, the other pics were unusable. I looked a week later and all the eggs had been removed to safety - what a task for tiny little black ants.