the fossilized outline of a hollow organic structure, as a skull or a mollusk shell, formed when mud or sediment consolidated within the structure and the structure itself disintegrated or dissolved. Also called Found on https://www.infoplease.com/dictionary/steinkern
1) Endocast 
the fossilized outline of a hollow organic structure, as a skull or a mollusk shell, formed when mud or sediment consolidated within the structure and the structure itself disintegrated or dissolved. Also called