[action]
No, the -- spiritual heart. [a beat, and then he says] When a heart is removed from its host, the darkness inside it consumes it, and it creates a monster that they call a Heartless. Usually hearts only make small, unimpressive Heartless, because most people don't have a lot of darkness in them.
So when a human loses their heart -- usually because a Heartless took it -- the heart becomes another Heartless, and the body dies or becomes a Nobody. [make sense? kind of?]