steinkerns

Steinkerns are fossilized internal molds of extinct organisms, primarily shells or hollow structures. They form when an organism, such as a mollusk, is buried in sediment. Over time, the original shell material dissolves, but the sediment that filled the hollow interior hardens, preserving the shape of the organism's inside. This internal mold is the steinkern.

These fossils are valuable for identifying extinct species, especially when the external shell is not preserved. Steinkerns can reveal detailed information about the internal anatomy of the original organism, such as the shape of organs or muscle scars. They are found in sedimentary rocks of various ages, from the Cambrian period to the present.

The term "steinkern" is German, meaning "stone kernel." The preservation process requires rapid burial to prevent decomposition and subsequent filling of the void by sediment before the original structure is completely destroyed. While most commonly associated with mollusks like ammonites and gastropods, steinkerns can also form from other organisms with hollow parts, such as trilobites or even some plant structures. Their study provides crucial insights into the paleoecology and evolution of ancient life.