Mantis shrimp

Last night I was watching a documentary about mantis shrimp. They are really cool and look like they are a mix of  Preying mantis and Lobster looking thing there is also a special species that has arms that can punch and crush crab and snail shells. They are also very territorial and live in burrows under the water. They will fight others of their species and kill the. They also have sex just like humans. Its really nasty and I cant believe that they showed that on TV. Finally they have spikes in their arms so that if they wanted to stab you while punching you they can.