Onigiri (お握り or 御握り; おにぎり?), also known as omusubi (お結び; おむすび?) or rice ball, is a Japanese food made from white rice formed into triangular or oval shapes and often wrapped in nori (seaweed). Traditionally, an onigiri is filled with pickled ume (umeboshi), salted salmon, katsuobushi, kombu, tarako, or any other salty or sour ingredient as a natural preservative. Because of the popularity of onigiri in Japan, most convenience stores stock their onigiri with various fillings and flavors. There are even specialized shops whose only products are onigiri for take out.