That was about as unfathomable to them, as it was to me that my mother's family would purchase an ice block every week to keep food in the ice box cold.
Ice box ... because they didn't have a refrigerator.
After I'd explained what little I know about genetic engineering and how over many years, watermelons that produced smaller and lighter seeds were produced over and over again, the kids interrupted me and asked, "So, have you ever seen a real live dinosaur?"