Hindu temples typically have Kalasam at the top of temple towers. These Kalasam in form of inverted pot is one of the prominent symbol of temples. Periodic renewal of temple is called kumbabishekam centers around Kalasams, when elaborate rituals are performed along with renewing the temple's physical structures.

Most Kalasam are made of metal and some of stone. View of Gopuram (Temple Tower) is one of the important rituals of hindu worship along with view of Kodimaram (Temple flag mast). Elaborate Gopurams were built as worship of sky above, these Gopurams were topped with ornamental Kalasams.

http://www.thehindu.com/news/cities/Madurai/article2084130.ece