Images of Hindu deities are typically anthropomorphic, Lord Shiva being the exception. The Puranas contain a legend in which Brahma and Vishnu once fought each other for supremacy. To end this and establish His pre-eminence in the trinity, Shiva manifested as a pillar of fire whose dimensions were unfathomable. This towering effulgence, without beginning or end is the lingam (shivling), the abstract, aniconic form of Shiva. Devotees believe that Shiva exists in their hearts in the form of a constant flame.
In sculpture, the lingam is shown as arising from a repository called the yoni. Together, they are said to symbolize the indivisibility of the male-female principles (the yoni being representative of Devi, the Mother Goddess).
Western scholars and philosophers have opined that the lingam is a phallic symbol. This however, is disputed by Indian philosophers and religious figures like Swami Vivekananda and Swami Sivananda who point to the absence of such interpretations in Vedic literature.
Famous shrines dedicated to Shiva are the twelve “Jyotirlingams” (lingams of fire) scattered across India. At Amarnath, in the remote reaches of the Western Himalayas, a stalagmite in the shape of a lingam, formed from ice dripping onto the floor of a cave, is a revered pilgrimage site.