The Malacostra, were race of lobster people from the planet Neptune, who were led by a giant member of their species known as Big Snapper. Big Snapper had realized that Neptune was becoming uninhabitable to his people, so he journeyed to find a new home, which ended up being Earth. When his subjects fled years later, they found that Big Snapper had mated with local lobsters and was ruling his own kingdom. Cursing his former subjects, he forced them to become land-dwelling blue humanoids. This curse could only be undone by finding the "Royal Roe" - the last lobster on earth that carries Big Snapper's bloodline.
After Gabrielle Lau tells the story of this species to Casey Jones, her boat is attacked by the Malacostra, who have found the Royal Roe. They summon Big Snapper, who also turns the Malacostra back to normal, and attacks Casey. Casey kills Big Snapper with depth charges from the Malacostra's stolen Coast Guard ship.