Each of the four chimerae are 2/2 artifact creatures for 
. Each has an ability that it can transfer to other Chimera brethren when it dies. And each was illustrated by Mike Dringenberg, artist behind several other Mirage block cards and, more recently, the Talisman of Indulgence, Damping Matrix and Jinxed Choker.
In the Chimera illustration below (Brass-Talon Chimera), note how the parchment behind the creature bears a sketch of a fantastic cat creature. It actually is the Brass-Talon itself, merged with the other chimerae.
If you look closely, all the Chimerae have this "cat-tomaton" and other Chimera images somewhere the background. If you were to line up all the background images, the foreground Chimerae would come together as a sort of collage, and it would look something like this: