Sue and I used to find egg shells on our kitchen floor all the time when we lived in Scotland, then one day the culprit was found my three year old son Robert was taking them out of the fridge and throwing them on to the floor for our Cocker Henry. Henry's party trick was to retrieve eggs with out breaking them, I guess my son had seen this and was helping.
Teal has a couple of raw eggs a week including shell and occasionally scrambled with a cooked fillet of trout if I have one spare, this being her favourite food.