<a href="https://en.wikipedia.org/wiki/ambigram" class="extiw" title="en:ambigram">Ambigram</a> <a href="https://en.wikipedia.org/wiki/Tessellation" class="extiw" title="en:Tessellation">tessellation</a> <b><a href="https://en.wikipedia.org/wiki/OK" class="extiw" title="en:OK">OK</a></b>. 90° rotational symmetry. Four orientations. Created from a <a href="https://en.wikipedia.org/wiki/pentagon" class="extiw" title="en:pentagon">pentagon</a> containing two <a href="https://en.wikipedia.org/wiki/Right_angle" class="extiw" title="en:Right angle">right angles</a> (isohedral type IH28 from the book <i>Tilings and Patterns</i> by <a href="https://en.wikipedia.org/wiki/Branko_Gr%C3%BCnbaum" class="extiw" title="en:Branko Grünbaum">Branko Grünbaum</a> and <a href="https://en.wikipedia.org/wiki/Geoffrey_Colin_Shephard" class="extiw" title="en:Geoffrey Colin Shephard">Geoffrey Colin Shephard</a>).
<a href="//commons.wikimedia.org/wiki/User:Basile_Morin" title="User:Basile Morin">Basile Morin</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>