Wedge-tail Triggerfish
Credit: Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution.

You can call it a wedge-tail triggerfish, or you can do as the Hawaiians do and call it "Humuhumunukunukuapua'a." This reef fish erects its doral spines when threatened, the smaller, shorter spine locking the first into place. When threatened, the fish wedges itself into reef rocks with this quick-deploy system.