Yoni is a Sanskrit word that has been interpreted to literally mean the womb, and the female organs of generation. It also connotes the female sexual organs such as "vagina", "vulva", and "uterus", or alternatively to "origin, abode, or source" of anything in other contexts.
The “prescribed” use of a yoni egg, according to proponents, is pretty simple. You insert the rock into your vagina for anywhere from a few minutes to overnight — ideally, every day. If you've heard people talk about the benefits of healing crystals, the spiritual benefits of yoni eggs will sound familiar.