Irori are a type of traditional sunken hearth

Hearth

In common historic and modern usage, a hearth is a brick- or stone-lined fireplace or oven often used for cooking and/or heating. For centuries, the hearth was considered an integral part of a home, often its central or most important feature...

 common in Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

. Used for heating the home and cooking food, irori are essentially square pits in the floor with a pot hook, or jizaikagi (自在鉤). These hooks generally were hollow bamboo

Bamboo

Bamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....

tubes containing an iron rod, with an attached lever, often shaped like a fish, that would allow the pot or kettle to be raised or lowered.