>>10309111It's implied here.
Wrap Trap's concept of a character with exposed internal body led Mayer to develop the flesh peeling Hordesman (they even have the same pose). So it's not a huge logical leap to assume that all those exposed chunks might have had bandage bits plugged in and could be taken out to reveal what was inside. See how deep and perfectly square cut they are? And a mummy with removable bandages just makes sense