[SpaceBar]

It appears so far to be legit. The rectangular stone was held in place with leather thong as a form of body adornment. Interesting if true since it seems to show a recurring archetype in the human psyche.

[MHGinTN]

Quite Jungian of you ...

[BTerclinger]

Urim v' Thummim... ("lights and perfections"). 12 stones (1 for each tribe), bejeweled breastplate worn by the Jewish High Priest; the priest would pray, the stones would light up signifying an "answer".

more info here: https://www.chabad.org/library/article_cdo/aid/4427467/jewish/What-Were-the-Urim-and-Thummim.htm

and here: https://en.wikipedia.org/wiki/Urim_and_Thummim#Name_and_meaning