Section through the ivory tooth of a mammoth from Siberia
Hannes Grobe, <a href="//commons.wikimedia.org/wiki/User:Hgrobe" title="User:Hgrobe">Hgrobe</a> 21:21, 4 July 2006 (UTC)
CC BY-SA 2.5
<span class="int-own-work" lang="en">Own work</span>