Illustation of the different types of <a href="//commons.wikimedia.org/wiki/Symmetry" title="Symmetry">symmetry</a> of <a href="//commons.wikimedia.org/w/index.php?title=Life&amp;action=edit&amp;redlink=1" class="new" title="Life (page does not exist)">life forms</a> On <a href="//commons.wikimedia.org/wiki/Earth" title="Earth">Earth</a>. Display at the <a href="//commons.wikimedia.org/w/index.php?title=Field_Museum&amp;action=edit&amp;redlink=1" class="new" title="Field Museum (page does not exist)">Field Museum</a>, <a href="//commons.wikimedia.org/wiki/Chicago" title="Chicago">Chicago</a>. The forms with bilateral symmetry can have heads. Life Forms with other types of symmetry have corresponding organs, if not a head.
CC BY 2.0
<a href="https://en.wikipedia.org/wiki/en:Image:SymmetryOfLifeFormsOnEarth.jpg" class="extiw" title="w:en:Image:SymmetryOfLifeFormsOnEarth.jpg">w:en:Image:SymmetryOfLifeFormsOnEarth.jpg</a>