IIRC, there wasn't an actual body beneath that robe; I think it was darkness covering a heart.well i dont think any theory is fullproof. but how did he not have a human body he wore that brown robe and could talk...
Bodies in the KH universe are usually associated with features of the human body. That's why nobodies have humanoid forms while heartless have monstrous forms.He didn't have a "body" so to speak. This is one of the KH concepts I don't understand. Heartless aren't supposed to have physical forms, yet they can scratch people with their claws or just charge them and hurt them.