Urechis unicinctus (Korean: gaebul) is a species of marine spoon worm. It is widely referred to as the fat innkeeper worm or the penis fish.
U. unicinctus, like other Urechis, lives in burrows in sand and mud. It gets the name “fat innkeeper worm” because the tunnels it creates often contain other animals.
This spoon worm is commonly eaten raw in Japan and especially Korea. This is often eaten with salt and sesame oil in Korea. Live gaebul is cut into tiny pieces and served raw and wriggling.
In Hokkaido, Japan, this is called ruttsu and served as sashimi.The taste of gaebul is similar to the taste of clams and it is not unusual to be sprayed with salt water while chewing on it.
In Chinese cuisine the worm is stir-fried with vegetables, or dried and powdered to be used as an umami enhancer. In particular, the worm is considered an important ingredient in Shandong cuisine and is used in numerous recipes.
In addition to its close looks to a part of the male anatomy, it is known for its aphrodisiac effects.