Lingodbhavamurti is an iconic representation of Lord Shiva. It can be said that this is the basis of Shiva Linga Worship. It is being worshipped as the central deity in all the Shaivite temples.
According to the Legend, there exists a story which depicts the origin of Linga. This Story is found in the epics like Shiva-Purana, Linga-Purana and Vayu-Purana. The Story goes in this way: Lord Vishnu and Bhrama were engaged in an argument that both are superiority over one another. Then there appeared before them – a huge lingam of fire.
Bhrama assumed the form of a swan and flew upwards, while Vishnu assumed the form of a boar, and burrowed down into the earth to trace the origins of this column of fire. While Bhrama was flying upwards, he saw the petals of a ketaki flower drifting down. Brahma being tired by the failed efforts to reach the top of the mysterious column of fire, he requested the flower to comply to his lie that he had seen the top of the column where the flower had previously resided.
Accompanied by his compliance, Brahma confronted Vishnu and asserted that he had discovered the origin of the cosmic column. Shiva appeared in enraged mood, out of this column of fiery lingam bearing the trishul in his arms. He addressed both Vishnu and Bhrama in a thunderous voice, explaining that the two were born out of him, and that the three were then separated out into three different aspects of divinity. He also cursed Bhrama for his Lie, so that he would not be worshipped in temples on earth.