Shalgrama literally means "found in the village where the sal tree grows". Shila means "stone". However the shalgrama shila is not a stone but an ammonite fossil, found in different shades of black. It is considered to be a stone and worshipped by Vaishnavas, who believe it originated from different parts of Vishnu`s body. Shalgrama shilas have holes with spiral grooves on the sides which are said to resemble Vishnu"s discus.
The Brihaddharma, Bhagavata and Kurma Puranas all testify to the sanctity of the shalgrama shila; in fact, the Kurma Purana identifies "shalgrama" as a village on the banks of the river Gandaki (a tributary of the Ganga), so named for its sal trees.
The shalgrama shila is worshipped in many homes even today. It is believed that worshipping the shalgrama shila frees one from the cycle of rebirth . It is supposed to be owned only by Brahmins, and is treated like an heirloom. The Atharva Veda states that a Brahmin`s house without a shalgrama shila is as impure as acremation ground. The water in which a shalgrama shila is washed is considered to be a cleanser of sins. It is also believed that imbibing just one drop of shalgrama water gives the same merit as can be achieved from performing every sacrifice and bathing in every tirtha.
The Varaha Purana forbids women from touching the shalgrama shila. It states that all the merits they have earned by following their karma and by praying are nullified if they touch the stone. They are permitted, however, to worship the shalgrama shila from afar or through those men allowed to worship it. Even Brahmin women are not permitted to worship the stone nor can they inherit it. If there is no male heir, the stone is passed on to another Brahmin.
The most popular legend about the origin of the shalgrama shila is the one associating it with tulasi or basil. According to the Devi Bhagavata Purana, Vishnu had three wives: Sarasvati, Lakshmi and Ganga. Once Lakshmi and Sarasvati quarreled and cursed each other. Sarasvati`s curse turned Lakshmi into a tulasi plant and forced her to live on earth forever. Vishnu, however, intervened and modified the curse, saying that Lakshmi would remain on earth as tulasi until the river Gandaki flowed from her body. In the meantime, he would wait by the riverside in the form of a stone to take her back to heaven. This stone was the shalgrama shila, which remained on earth as a representative of Vishnu.
Therefore, the shalgrama shila and tulasi plant are always worshipped together as Vishnu and Lakshmi. Since they are so closely associated, every year in the month of Kartik, the Vaishnavas marry a tulasi plant to a shalgrama shila in an elaborate ceremony.
Today, the stone can be found in the bed of the Gandaki river, which flows down through present-day Nepal and joins the Ganga in Bihar. It is also found near the Narmada river. The largest and heaviest shalgrama stone can be seen at the Jagannath Temple, dedicated to Vishnu, at Puri in Orissa.