The presiding deity is MahaVishnu , in standing posture with four hands carrying Sankhu(conch), Sudarshana chakram (a serrated disk), lotus and mace. He is worshipped as Balakrishna, the full avatar (Purnaavatara ) of Mahavishnu. The idol is made of a rare stone known as Patala Anjana. The square Sreekovil is the sacred sanctum Sanctorum of the temple, housing the main deity of Lord Krishna. Within the temple, there are also the idols of Ganapathy, Sree Ayyappa and Edathedathy Kavil Bhagavathy. Only Hindus are allowed inside the temple and the walls of the sanctum sanctorum are inlaid with exquisite mural paintings and carvings. It is at this temple that Melpathur Narayana Bhattathiri composed his well-known Sanskrit devotional poem 'Narayaneeyam'. Guruvayur is the site for weddings and Annaprasanam, the first feeding ceremony of a child.