Underwater archaeological exploration off the Poompuhar coast in Mayiladuthurai district has yielded a torpedo jar fragment, four ancient ring wells and more than 250 ceramic pieces. The torpedo jar, thought to have come from West Asia, lay about 10 metres deep and 2 km offshore; such tubular vessels carried liquids like wine and oil on ships. The ring wells, 60–65 cm in diameter, may point to an ancient palaeochannel. Poompuhar, the ancient port city also called Kaveripoompattinam, is being studied for its remains and for changes caused by coastal erosion.