Question regarding some certain fruits…

Just finished part 8 and loved it but something thats been on my mind,What is the connection between the locacaca fruit and the rock humans? I sorta got stone mask/pillar men vibes where the pillar men made the masks, But whats the deal/history with the rock humans and the fruits? They seem to Be quite fond of them and and seem to know much more about them then other characters so it left me curious