Salagrama or Shaligram is a fossilized shell used in South Asia as an iconic symbol and reminder of the god Vishnu as the Universal Principle by Hindus of Vaishnavite and Smarthist sects. Shaligrams are usually collected from river-beds or banks such as the Gandaki River in Nepal. They are considered easy to carry and popular in certain traditions of Vaishnavism, as an aniconic representation of the divine. They are typically in the form of spherical, black-coloured Ammonoid fossils of the Devonian-Cretaceous period which existed from 400 to 66 million years ago.