Omusubi is another term for Onigiri which refers to a Japanese snack made of rice formed into triangle or oval shapes and wrapped in Nori (edible seaweed). Traditionally, the Omusubi is filled with pickled salted plum fruit called Umeboshi, salted salmon, bonito shavings, Katsuobushi, or any other salty or sour ingredient. In practice, pickled filling which is used for Omusubi or Onigiri is used to preserve the rice. Since the Omusubi is one of the most famous and popular snacks in Japan, most convenience stores in Japan stock Omusubi in many popular fillings and tastes. Specialized shops, called Onigiri-ya, offer handmade rice balls for take out. Omusubi is also spelled O-Musubi.