The "egg cartons" are spacers between explosive reactive armor places. The interesting part isn't that there are egg cartons but that there's only egg cartons -

The "egg cartons" are spacers between explosive reactive armor places. The interesting part isn't that there are egg cartons but that there's only egg cartons - the ERA plates are missing. My favorite story of Russians and armor plates was the dead Russian soldier who was found with his armor vest plate replaced by a stolen MacBook.