Simply put: 1. From the appearance, the inferior sea cucumber is gray-black, full-bodied, slightly salt-permeable and bald, with a distance of about 5 mm. If you rub its epidermis with your hands, your hands can be dyed black. 2. From the inside: after the inferior sea cucumber is broken by hand, its inside is full of gray-black impurities. Specifically: First of all, in addition to shopping places with reputation guarantee, it is best to master a little common sense to distinguish the quality of sea cucumbers: 1. Complete and correct shape. This is very important, because it can explain the freshness and quality of sea cucumber. After traders remove the corrupt parts, they often leave incomplete sea cucumbers; In addition, the twisted and shriveled body shape indicates that this kind of sea cucumber has been fishing for a long time, and this kind of sea cucumber is easy to be polluted by microorganisms and lead to deterioration; 2. Dry enough, that is, the water content is less than 50%. Because sea cucumber is expensive, the lower the water content, the more affordable it is. In order to gain high profits, some merchants often mix too much water into sea cucumbers, which not only makes consumers suffer in price, but also benefits the growth and reproduction of microorganisms, which is not conducive to the preservation and quality assurance of sea cucumbers. 3. Light mouth, strong and shiny. Whether it is firm and shiny indicates the nutritional richness of sea cucumber. Sea cucumbers living in food-rich waters are mature, with high nutritional content and high value. 4. The size is even, and there is no sand in the abdomen. In order to make huge profits, some vendors use illegal means to fill the belly of sea cucumbers with sand to increase their weight.