800 light years away

Well actually not! I am sat at my desk today and can't be bothered to go out with my camera. This is going to be a longer story than normal from me, but read on as I think it's worth it.

We have a cottage in Provence - some pictures here - and in the area are these incredible natural round stones that the locals refer to as dinosaur eggs. These eggs are normally at least 1 metre across and are pretty amazing to see, especially as they are often half buried in the ground. No one knows how they were formed.
Whilst out walking one day I found a tiny one - about 3cm diameter - that is almost perfectly round. It has pride of place on the window sill in my office. Today though it's been blipped. Sorry to inform you it's not a planet and I have not connected my camera to a huge telescope - just a good old macro lens and a steady(ish) hand.
The really odd thing about this egg is its size and the fact it came from a slightly different area than the normal big ones? I've asked some locals and no one has seen one this small.