Rai

Level 2 – Bergie Web

I assume this is referring to Rai stones. A rai stone (Yapese: raay[1]), or fei stone[2] is one of many large artifacts that were manufactured and treasured by the native inhabitants of the Yap islands in Micronesia. They are also known as Yapese stone money or similar names.

LINKS
https://en.wikipedia.org/wiki/Rai_stones