Pretzel baked in the shape of a (-2,3,7) pretzel knot
<a href="//commons.wikimedia.org/wiki/User:Zephyr_the_west_wind" title="User:Zephyr the west wind">Zephyr the west wind</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>