Once Parvati mocked Shiva's penance for betterment of the world. Shiva wanted to condemn her act and directed her to go to the earth from Kailasam (Shiva's abode) to do penance. Parvathi in the form of Akilandeswari as per Shiva's wish found Jambu forest (Thiruvanaikoil) to conduct her penance. She made a lingam out of water of river Cauvery (also called as river Ponni) under the Venn Naaval tree (the Venn Naaval tree on top of the saint Jambu) and commenced her worship. The lingam is known as Appu Lingam (Water Lingam). Siva at last gave darshan to Akilandeswari and taught her Siva Gnana. Akilandeswari took Upadesa (lessons) facing East from Shiva, who stood facing west.