Rock Humans returning

This new chapter has made me come up with two ideas of what could be happening with the Usagi's mum scam plot. Firstly, Meryl Mei seems really sketch, not much evidence but I just don't quite trust her. Secondly I believe if there were going to be rock humans in part 9 this is where they will appear. Many rock humans in JoJolion were doctors, and a secret organ harvesting ring in Hawaii being ran by rock humans doesn't seem misaligned with activities a group of rock humans could be included in.