The Shock beast were a species of Space Pirate from Metroid 1.5 whose design was incorporated into Metroid Prime 2: Echoes as the Pirate Troopers, though without the described attributes. It was the first depicted enemy from the game, shown in the first short trailer for Echoes.
Notably, the concept art identifies them only as Space Pirates.
•Shock beast: Standing 10 feet tall, the shock beast is another Space Pirate/ Alien Hybrid. It is similar to storm troopers in respect to its loyalty and stupidity. It is the standard shock trooper of the Alien fleet and carriers a high-powered pulse rifle and frag-grenades. In addition to mechanical weapons, it can also self-destruct when in danger or low on health. Again, the blast radius would kill anything within a 20-foot radius.
•Due to a genetic flaw, the heart and lungs (on its backside) of the shock beast are exposed, making it an easy kill. Since the ship’s AI has noticed the design flaw, later versions have an armored carapace that must be destroyed in order to hit the vital areas, much like the Baby Sheegoth.