I can't make it any clearer - I have pointed out the locations of all of the egg stones that I know about. Some may have moved since. they are all natural boulders eroded from softer rock. The only mystery is why people have to invest them with bogus paganism and then deface them.

Stones under churches? - I don't want to go there again, but many are located where it would be difficult not to find perfectly natural sarsens beneath them - its called geology.