Shaligram or Shila is a fossilized seashell stone which is worshiped as a symbol of god Vishnu worldwide in mostly all Vaisnava Sampradaya (culture) as well as in hindu devotees home. These are usually collected from the banks of Gandaki River in Nepal, espacially at Muktinath. Shaligrams can be identified according to specific representation mentioned in religious scripts. There are different characters and chakra with form of lord vishnu that symbolizes different saligrams. They are typically in the form of spherical, black coloured Ammonoid fossils with chakra or without it or might content golden colors.
We can find the largest and heaviest Shaligrama at the Jagannath Temple - dedicated to Vishnu, at Puri in Orissa, India