FILE – In this Oct. 2, 2015, file photo, cow dung cakes are left to dry on the wall of a house in Allahabad, India. In India, where Hindus have long worshipped cows as sacred, cow dung has been used for centuries as fuel for fires – whether for heat, cooking or in Hindu ritual fires, where it’s a necessity. Now, online vendors like Amazon, ShopClues and eBay are selling cow dung patties to India’s ever-increasing urban population, especially those who grew up in villages. (AP Photo/Rajesh Kumar Singh, File)