The Lingam is known to be one of the oldest religious symbols known to humans. Shiva Lingams are said to symbolize the Divine Creative Manifestation, and they also known to balance the masculine and feminine energy forms within everyone. The markings, also known as the yoni, symbolize the feminine energy, the seed which is fertilized to manifest the creative power in the dance of the cosmos. Geologists theorize that the iron oxide, of which the yoni is composed, was impregnated in the river bed millions of years ago by a meteorite. The Shiva Lingam is a stone of insight, allowing you to recognize and let go of things (feelings, emotions, etc.) that no longer serve you or have been outgrown.
