This is a scanning electron microscopy image of an array of aluminium oxide (a ceramic material) micropillars made by 3d printing. They are roughly the width of a human hair and require special handling to ensure their integrity.
<a href="//commons.wikimedia.org/wiki/User:Ezrado" title="User:Ezrado">Ezrado</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>