The size of herring stone has a great relationship with the age and size of herring. Generally speaking, the herring with larger size and longer age has larger herring stones.

Although the herring stone has high value, not every herring will grow herring stone. Small herring will not form cuticle if they eat less snails.

Generally, herring that has grown for more than 5 years will often eat snails, and herring stones will be slowly found out. At present, there is no herring stone in farmed herring, and there are fewer and fewer wild herrings. It is entirely luck to get herring stone.

The concept of herring stone or herring stone powder is often found in the treasure-hunting chapters of fairy tales and the names of props to ward off evil spirits and detoxify in online games. Such as the novel "Ghost Blows the Lamp" and the online game "Love between Swordsman and Chivalrous Man 3".

The herring (black pomfret) with this stone, also known as snail green, belongs to the genus herring of CYPRINIDAE, a freshwater fish, weighing up to tens of kilograms. The fish likes to eat hard snails, and the herring stone is a hyperplastic horny pad in the throat below the occipital bone of herring, which is used to help crush snails for many years. Grass carp and carp are also found, and other fish generally do not have this stone, so it is rare and precious. The herring stone is stable in material and can be stored for a long time after being taken down and dried naturally.