Shaligram is considered as Lord Vishnu himself. It is the stone worshipped by Vaishnavas mostly. Shaligram is also known as Shaligram Shila by the Vaishnavas, as they usually use that word.
Shaligram Shila is the sacred stone worshipped across the world. According to one of the Beliefs in Vaishnava, whoever worships the Saligram, must obey the strict rules without fail. The Saligram name refers to the village in the banks of river Gandaki. It is where the holy stones of Saligram Shila are collected.
It is believed that the legend “Brahma Sutra” tells about the Saligram in this way: In worship of Vishnu, Saligram is well practiced. It is universally accepted that Saligram Stone represents Lord Vishnu.
The largest and heaviest Saligram Stone is situated in Puri Jagannath temple. People worship usually small and medium Saligrams. The use of Saligram as a worship stone can be found earlier in the days of Adishankara.
The Legend of Saligram can be depicted in this way: Once, in anger Goddess Sarasvati cursed Goddes Lakshmi, which changed Lakshmi into a tulsi plant. She was made to live on earth forever. Lord Vishnu has interfered saying that Goddess Lakshmi would remain on earth til the river Gandaki would flow from her body. He waits by the riverside in the form of a stone to take her and this stone was the Shaligram Shila, which continues to remain as a representative of Lord Vishnu. That’s the reason the Shila Deities and the tulsi plant are always worshipped together as Lord Vishnu and Goddess Lakshmi.