These reptiles as drawn by M.C. Escher are fascinating. It seems impossible that these reptiles are able to fill a surface completly, however they do... due to the fact that the base of these reptiles is a regular triangle.
Note that the logo at the bottom right functions also as shortcut to the homepage of ZOMDir, and it is a trash can for removing a link with the built-in drag-and-drop functionality.
Note that a salamander is also a soul that cannot be destroyed.