"I'm not sure if they are. I think this might have just been a native lady? She had a lot of stuff like crystals and other odds and ends, but it's just a booth in the Willful Machine."

Which he was mostly interested in because...well, he prefers saltwater.

"Oh. Why don't humans just drink salt water?"

He's noticed a lot of the water they drink (and offer him) is all fresh water, which Luca can drink, but he definitely prefers salt water.