It's shaped like a leaf. It's colored like a leaf. It even sports the vein-like structures typically found in a leaf's spongy mesophyll layer. But this is no leaf.
It's a moth.
It's Uropyia meticulodina, to be exact, and it's one of the finest examples of camouflage the animal kingdom has to offer. As REALMonstrousities' Joseph Jameson-Gould puts it, "It's like one of those optical illusions that still work even when you know it's a trick."