Octopus traditionally fills the center of a Japanese takoyaki ball.
Takoyaki are made by pouring a wheat-flour batter into the round cavities of a specialized iron pan. A small piece of octopus, called tako in Japanese, is placed in each portion before the balls are turned repeatedly with picks. This produces a browned exterior and a soft, often molten interior.
The snack was created in Osaka in 1935 and became popular at food stalls, festivals, and casual restaurants. Standard toppings include a sweet-savory takoyaki sauce, Japanese mayonnaise, aonori seaweed, and dancing bonito flakes.
Modern vendors sometimes offer variations containing shrimp, cheese, sausage, or vegetables. Those versions are adaptations rather than the traditional filling. The word takoyaki itself combines tako, meaning octopus, and yaki, meaning grilled or cooked.