Haijuan, a type of shell, is medium to large in size, slender, and has many layers of snails. The shell surface usually has many spiral ribs and significant thick longitudinal ribs. Discovered on the west coast and Penghu Islands. From the Yellow Sea to the South China Sea, Indonesia, Malaysia, and Singapore. Keelung, in the western waters of Taiwan, Mosquito Pit in Gongliao Township, Taipei County, Lukang in Changhua County, Kaohsiung County, Penghu, Penghu Inland Sea, Danshui in Taipei County, Baishawan Coast in Taipei County, Hualien Coast, Anping in Tainan City, Donggang in Pingtung County, Jinning in Kinmen, Jincheng, Jinsha, Jinhu, and Lieyu. Mature individuals have a well-developed and broad outer lip on their shell; The water pipe trench is also very deep, and the leading edge of the outer lip usually extends beyond the water pipe trench.