This is a "tree lobster"

Dryococelus australis is a stick insect that grows up to 8" in length and was thought to be extinct until a group of them were found here -

- on the uninhabited islet of Ball's Pyramid, which is the world's tallest volcanic stack.  An interesting story about attempts to protect and conserve this invertebrate is in The New York Times.

First image cropped for size from the original (credit John Francis Peters).  Credit for the second to John White Photos, via Alamy.