Smashers like the peacock smasher (Odontodactylus scyllarus) above are sometimes known as thumbsplitters. These are the guys that can smash through glass and various other things. To do this they use reinforced clubbing appendages called dactyls.
Much cooler in my view though are the other kind, the spearers such as the Lysiosquilla sp. below.
These chaps don't run about smashing stuff but rather sit in their rather well constructed holes all day. When a fish swims above they drive their harpoon-shaped dactyls up into it and spear themselves a meal - which is cool, unless you're the fish. All mantis shrimps have cool compound eyes in addition to their clubs or harpoons and they really are neat little (or, in the case of a large spearer, quite big) animals.
This is another spearer, probably also a Lysioquilla, and like the peacock smasher I found it on Monad Shoal in the Philippines. Monad shoal is a cleaning station famously frequented by huge manta rays and thresher sharks but it pays to keep one eye out for the little stuff as you can find all sorts.