<a href="//commons.wikimedia.org/w/index.php?title=Concretion&amp;action=edit&amp;redlink=1" class="new" title="Concretion (page does not exist)">Concretion</a> with septarian cracks filled with <a href="//commons.wikimedia.org/wiki/Calcite" class="mw-redirect" title="Calcite">calcite</a>. Scale in mm.
<a href="//commons.wikimedia.org/wiki/User:Wilson44691" title="User:Wilson44691">Wilson44691</a>
Photograph taken by Mark A. Wilson (Department of Geology, The College of Wooster).