https://eurekalert.org/pub_releases/2020-01/f-sf-acd012820.php

                                                                                                                      haseente

  Reversible Figure. More to that: https://www.philosophie-wissenschaft-kontroversen.de/details.php?id=229412&a=t&autor=Wittgenstein&vorname=Ludwig%20&thema=Hase-Enten-Kopf