A shaligrama shila (Devanagari: शालिग्राम शिला Śāligrāma-śilā), also rendered as shaligram, is a particular variety of stone collected from riverbed or banks of the Kali Gandaki, a tributary of the Gandaki River in Nepal, used as a non-anthropomorphic representation of God Vishnu by Hindus. They are typically fossils of ammonite shells from the Devonian-Cretaceous period of 400 to 66 million years ago. The fossils are considered holy by Hindus because Madhavacharya received it from Vyasadeva, also called Astamurti, and also they resemble symbols associated with God Vishnu, mainly the Shankha (conch shell).