Mantis shrimp are neither shrimp, nor mantis, they are a separate group of 450 species called stomapod.
Sporting a thick shell that covers the back of the head and the first four segments of the main body, mantis shrimp are among the most efficient crustacean predators. Typically growing to around 10 - 15 cm in length, this group of animals have some of the most complex eyes in the world, including the ability to see polarised light.
Smashing mantis shrimp have two specialised calcified "smashing clubs" at the front of the body that are used to smash crab and clam shells at over 50mph in just a fraction of a second, and are known to crack and punch holes in aquarium glass.
Smashing Mantis Shrimp are solitary and territorial creatures, making burrows in hard seabed or coral cavities which are used as sites for mating and for keeping their eggs safe.