Psammechinus microtuberculatus - <i><a href="https://it.wikipedia.org/wiki/Psammechinus_microtuberculatus" class="extiw" title="it:Psammechinus microtuberculatus">it:Psammechinus microtuberculatus</a></i> © Massimiliano DE MARTINO - CC BY-SA 3.0 - Wikimedia Commons