Tongue shellfish originated 542 million years ago. In the long years, the earth has undergone several major changes, so many creatures have become extinct and many creatures have begun to be born. There are also some creatures that have adapted to the test of the environment and survived again and again in history. They are called living fossils because of their long life, some ancient characteristics and great research value.
Among many living fossil animals, the oldest creature in the world is the tongue-shaped shell, which may have originated before Cambrian. They are not very big, they are brachiopods without hinges, and they like to make holes in shallow mudflats. This creature, which has existed for more than 500 million years, is of great significance for people to study the differentiation of Cambrian brachiopods.
Tongue shellfish mainly live in temperate and tropical waters. Their shapes are tongue-shaped or oval, and their shell walls are brittle and thin. They live in caves most of the time. They are also very small, the shell is about 4 cm long and the handle is about 6 cm long. It is such a fragile creature that has successfully withstood the changes of the world and survived the long history.
In 2004, it was reported that in Chengjiang Fossil Repository, the newly discovered Xishanbei in Haikou was a brachiopod with a tongue-shaped shellfish, but it was probably not a cave animal after identification. But its discovery enriches the eyes of brachiopods and has important research significance. The environmental information provided by tongue-shaped shellfish has little effect on stratigraphic correlation, but it is an important member of Cambrian brachiopod fauna.