The image shows the centre of a polished slice of a petrified tree from Arizona. After enlargement of the image it is possible to discern the tunnels and cavities of living things deep inside the tree. They lived some 230 million years ago in the late <a href="https://en.wikipedia.org/wiki/Triassic" class="extiw" title="w:Triassic">Triassic</a>.
<a href="//commons.wikimedia.org/wiki/User:Michael_G%C3%A4bler" title="User:Michael Gäbler">Michael Gäbler</a>
CC BY 3.0
Self-made Scan with "Epson Perfection 4490 Photo" from the middle part (size 15,34 x 18,04 cm) of a polished slice of petrified wood from Arizona. This file is large enough to make a fine print.