YELLOW MONSTER TESSELLATION
by Sophie D. of Glasgow, Scotland
These monsters look a bit like Sponge Bob Squarepants' happy, dancing friend, the starfish.
Sophie D.'s picture is a good tessellation because it can completely fill a 2D surface without gaps and without overlaps.
This tessellation repeats via the translation (slide) method. That means the monsters are all (dancing? Running?) in one direction: no spinning, no individuality as they choose which way to move.
This tessellation is a clear example of the "TTTT" type in the Heesch tessellation classification system. That means, each monster touches four other monsters (that's why there are 4 "T"s), and translation-- that is, sliding to an adjacent place without spinning or facing the other way-- is the only way they repeat.