An ancient heap of shells at Sakatsuji Shell Midden in the city of Toyohashi, Aichi Prefecture, most likely served as a clam processing site in the latter half of the mid-Jomon Period, approximately 4,500 years ago, an investigation conducted by the city's board of education has revealed.

While there are ruins in eastern Japan that indicate organized production during the mid-Jomon Period — including the Nakazato shell midden, or mound, which is a national historic site in Tokyo's Kita Ward — it is extremely rare to find one in the Chubu region or further west. This latest discovery will provide important clues about the culinary lifestyle and economic activities conducted in the Jomon Period.

The Sakatsuji shell mound is one of the Muro cluster of seven shell middens in Aichi Prefecture.