If she didn't know much about the ocean, then the chances were even higher that they were from different worlds. Brook was about to tell her that it wasn't uncommon for such a thing to happen and that she shouldn't worry too much since, at least during the day, they were treated relatively well, but her comment about being dead changed his words entirely.

"Anything is preferable to death Lust-san, of that I can assure you!" he told her firmly, yet softly as the subject hit particularly close to home with him.

There wasn't anything to be had when you died except for bones. Brook may have been the exception to that, but otherwise that sentiment held true. And Lust certainly had the right train of thought to be saying as much.