Urechis unicinctus (simplified Chinese: 海肠; traditional Chinese: 海腸; pinyin: hǎicháng; Japanese: 螠虫 or ユムシ yumushi; ‹The template Korean is being considered for merging.› Hangul: 개불; RR: gaebul) is a species of marine spoon worm. It is widely referred to as the fat innkeeper worm or the penis fish.