The ancient nature of this temple is surprising. The holy pond ‘Rudratheertha’ is believed to have flowed touching the feet of this great temple.  It is long since this pond was given the name ‘Rudra-theertha’.  But it is to be guessed that, even before that, the divine presence of Lord Mahadeva was there. This temple not only makes us realize the depth of devotion to the Lord Siva, but it also reveals the strength and the power of ‘Siva-Vaishnava’ arts. This temple has an unbreakable relationship with Guruvayur Sreekrishna temple. After Lord Krishna’s ‘Swargarohana’ Dwaraka was drowned.  At that time an idol of Lord Mahavishnu was floating more on the water.  It was taken by ‘Guru and Vayu’ and they searched for an appropriate holy place to install it.  This idol was even adored by Lord Krishna and its eminence made even saints to worship it.  It is said that seeking the advice of Parasurama, Guru and Vayu reached Kerala also, in search of a holy place. They installed the idol on the banks of ‘Rudratheertha’ where the divine presence of Lord Siva is already there. Lord Shiva invited them pleasantly and installed the idol near his place of meditation.  Later he helped to shift the idol to the place where the present Guruvayur temple is situated.  The place from which the idol was shifted came to be known as ‘Mahimayoor’ and later as ‘Mammiyoor’.  The worshippers who come to worship Lord Krishna in Guruvayur have to visit Lord Mahadeva in Mammiyur. It is believed that the pilgrimage to Guruvayoor will be completed only after the visit of Mahadeva at Mammiyoor.  Even today this custom continues to be as before and it shows the relationship between these two temples. In Mammiyur Sree Mahadeva temple, there are other installations of sub Gods Lord Ganapathi, Lord Subrahmania, Lord Ayyappa. Moreover, there are the installations of Brahmarakshassu, Naga, Devi – everyone’s divine presence is already there and they shower their blessings on the worshippers.  Great prominence is given to the rituals in this temple.  Lord Krishna and Lord Mahadeva simultaneously shower their sacred blessings on the worshippers and this is a peculiarity which is seen only in this temple. Famous rituals and its benefits as believed are: Karuka mala  to Lord Ganapathi, Mala, Karuka homam, Ganapathi homam, Ottappa Nivedyam : to fulfil the wishes, to remove obstacles, to remove the plights of children and for their intelligence. ‘Maha Mrithyunjaya homam, Mrithyunjaya Pushpanjali : to liberate from all diseases and for sound health. Ekadasa Rudrabhishekam : to please Lord Mahadeva. It is  believed that it will bring about peace and prosperity. Varam oottu : to escape from the curses of Brahmins, from the miseries which is the result of the sins committed. Dampathi pooja : for peaceful marital life for the attainment of children. Uma Maheswara Pooja : to remove the obstacles that stand in the way of marriage. Lakshmi Narayana Pooja : for peaceful marital life, for financial gains, for the achievement of prosperity in the family. Brahmarakshassu Pooja : to remove the defects of the place. Rahupooja, Nagapooja : to remove all the miseries caused by the serpents. Bhagavathy seva Bhagavathy Pushpanjali : to remove the defects of ‘Chovva dosham’. Rigveda Dhara : it is very rare to conduct ‘Rigveda Dhara’ in the temples of Kerala.  In Mammiyur temple every morning, ‘Rigveda Dhara’ is done to Shiva and Vishnu.  Rigveda which is the most prominent of the four Vedas, is recited by famous vedic scholars everyday in this temple.