Casualty

A bit of a gruesome pic but I found this on the lawn. Had it just hatched and been taken from the nest (it couldn't have fallen) or had something stolen an egg before it hatched?
Our visitor left this afternoon to go to Glasgow to visit relatives for a few days before going to Manchester.
This evening we were in Falkland doing the 3rd of a series of trail races, went well and Mr Rat's sprained ankle is healing nicely.