SCIENTIFIC EDUCATIONAL CENTER science idea

Hermit crabs use the shells of gastropods as a refuge and shelter from dangers. Today, several hundred species of such crustaceans are known, plus several species of worms that resort to a similar defense strategy. However, recently a team of paleontologists from China and the UK discovered the oldest example of this behavior — fossils of worm-like animals that settled in the shell about 500 million years ago.
Four studied samples were preserved in sedimentary rocks that accumulated at the bottom of the ancient sea and today appeared on the territory of the Chinese province of Yunnan. Examining them, scientists have distinguished traces of conical shells, most likely left by chiolites - representatives of an extinct group of invertebrates close to mollusks. They are widely found in Cambrian sediments, but this time the shells were combined with the remains of other ancient marine animals — priapulids.
These worm-like invertebrates still live on the ocean floor today, preferring the cold waters of the circumpolar latitudes. Because of their external similarity to the penis, they were named after the ancient Greek god Priapus, who personified "masculine strength". Priapulids feed on dead organic matter and algae and have been burrowing for hundreds of millions of years: it is believed that they appeared during the Cambrian explosion, about 540 million years ago, when most types of modern animals arose. About 20 species of priapulids have reached our time. trilobites, marella and others.
Paleontologists attributed the fossils found in Yunnan to the genus Eximipriapulus. Not a single sample of priapulids was found separately from the shell, so scientists are sure that the animals did not just hide in them, but used the shells as a permanent shelter. The shape and size of these tiny organisms correspond to their shells, showing that they chose the shell "for themselves" with the same care as hermit crabs do. Until now, there has not been a single example of such behavior in priapulids — and not a single example of such antiquity.
The article was published in the journal Current Biology
PHOTO: Reconstruction of Eximipriapulus © Zhang Xiguang, Yunnan University
Source: naked-science.ru, sci-dig.ru