INDIA, April 19, 2012 (The Hindu, By Pradeep Chakravarthy): This is the part of a story on temple rituals, shodasha upacharas, and the meanings of the sacred objects used. Here, the deepa is explained.
Deepa or waving a lamp lit is an integral part of the upachara, for two reasons – it was the only means of light in the past; and its symbolism is of removing ignorance. As a consequence several types of lamps evolved – those that were stationary, those that were suspended from the ceiling and those held in the hand. Those held in the hand had the lamp in the front, the horizontal ‘S’ that served as two base pedestals. The space behind the lamp and the rear base had separate icons cast and fixed. Icons included a five-headed cobra, then called the nagadeepa. The cobra has been a symbol of fertility whose worship in the lesser Hindu traditions was absorbed in the Sanskrit tradition.
It could be an elephant, the gaja deepa, where the elephant symbolises royalty; the horse, a symbol of speed and valour, became the ashwa deepa. Siva temples had the rishaba, Siva’s mount. They also had the Purushamriga, an animal with the head of a man/sage. There is a minor reference to this ardent devotee of Lord Siva in the Mahabharata. In some temples, these icons were a similar pedestal without the lamp, in which case they were ritually shown to the deity much like a King would inspect his army and check if they were all in the best of condition.
Vishnu temples had a unique Kurma deepa, where the tortoise had in its rear a handle. The carapace of the tortoise had five small holes through which the wick was inserted. Against the belief that tortoise signifies ill omen, it is considered a symbol of stability and even today in Kerala, wooden seats are made in the same shape for use in Vedic rituals. Such rare lamps may have also been the whim of an aesthetic devotee and a master craftsman. There is no a specific textual reference that insists on a temple having this lamp.
Most of these lamps have been gone – auctioned off by temples or removed by unscrupulous collectors. What remains is the adukkudeepam, where each platter has several wicks in a circle and then there are smaller levels of platters, always of an odd number.
(See the source for more, and very interesting, information)