Bombardier beetle
Bombardier beetles are a family of ground beetles comprising over 500 individual species. When aggravated they have the ability to blast predators a noxious mix of chemicals from glands in their abdomen, hence the name 'Bombardier' beetle.
Defense mechanism and intellegent design
So complex and exact is the defence mechanism of the bombardier, involving secretion of hydroquinones and hydrogen peroxide in a 'reaction chamber' inside the very bowels of the beetle, that many creationists have championed the bug as being proof that evolutionary theory is a fallacy.
The individual components of the beetle's defence mechanism provide no evolutionary advantage by themselves. It is only when the system is implemented as a whole that the beetle can achieve a useful trait. [1]
Evolutionary theorists have attempted to argue that that evolution can account for these traits, but have so far consistantly failed. [2]