Very creepy, but I wonder if some of these children had seen programmes/videos/cartoons unbeknown to their parents and had formed their ideas from that. Even if they had been guarded from such stuff, maybe their little friends' parents hadn't been so vigilant. Also, children think quite logically, so putting your mummy in a jar to keep forever and not finding a jar big enough seems perfectly logical and sensible to a young child. Bones, blood, body parts etc don't carry the connotations they do in an adult's mind. As a child of about four, I was convinced I was two people, the alter ego being a much older person, a young woman with a similar name. This lady spoke to me and seemed often to disapprove of my behaviour. My sister had a very bad imaginary friend called Martin who scribbled on her wallpaper and told her to wee in her bed. I think these events were quite normal psychologically, but interesting for our parents!