Cooloola Monster

Despite its name, this strange 1 inch creature is actually a distant relative of the cricket. Found in Australia (natch'), it was actually strange enough that they gave it its own family, the Cooloolidae.

It also spends its whole life underground, which makes perfect for diabolical gamemasters. Nothing like telling the player that his 12th level fighter just got munched by a giant, subterranean cricket.