Chemical structure of <a href="https://en.wikipedia.org/wiki/penguinone" class="extiw" title="w:penguinone">penguinone</a> or 3,4,4,5-tetramethylcyclohexa-2,5-dienone.
<a href="//commons.wikimedia.org/wiki/User:Dbc334" title="User:Dbc334">Dbc334</a>
2007-06-09
<span class="int-own-work" lang="en">Own work</span>