The spleen is an organ found in all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. <p><a href="https://commons.wikimedia.org/wiki/File:Illu_spleen.jpg#/media/File:Illu_spleen.jpg"><img src="https://upload.wikimedia.org/wikipedia/commons/d/d6/Illu_spleen.jpg" alt="Illu spleen.jpg"></a> From [Wikipedia](https://en.wikipedia.org/wiki/Spleen) Public Domain, <a href="https://commons.wikimedia.org/w/index.php?curid=1394146">Link</a></p>