The Mimic

The Mimic is a non-combat pet in Diablo III, added in patch 2.4.1. It drops from Menagerist Treasure Goblins.

Trivia

 * The Mimic will collect gold sitting on the ground for the player, even at the edge of the screen.
 * The pet's name, appearance and description are a likely reference to the Chest Monster cliché in fantasy. "The mimic made its first appearance in the original Monster Manual (1977), by Gary Gygax." It could also be possibly pointing at Mimics from Dark Souls series specifically (the release of Dark Souls 3 happened at the time of patch 2.4.1 development, and quivering is a characteristic feature of these monsters). Similar creatures exist in many other universes though.
 * The quote may also be a reference to The Luggage, which followed the wizard Rincewind around in the Discworld novels.
 * Upon closer inspection, the chest actually has a single eye located in the keyhole.