The Decapodians were a race of aliens who invaded the planet Earth in the 31st century.
Physisiology
Decapodians are essentially humanoid, but have an exoskeleton shell, claws for hands, four seemingly prehensile appendages above their mouths and no hair. They all speak with Yiddish accents, possibly because of these appendages. They also possess a fin-like crest that appears when they are enraged or aroused, as well as an ink gland similar to the Earth octopus. They have been known to use their ink while writ ing letters that require a personal touch. Decapodians also have a strange gland that produces foul odors when they are bored. Interestingly, they can still survive and stand upright without their shell, suggesting an endoskeleton as well as a shell intended simply for defensive purposes.
Internally, Decapodians are cold blooded and have a number of redundant organs, such as four hearts, that may be removed without fatal consequences.
Life Cycle
Decapodians mature through a long series of larval stages before attaining the humanoid, fully grown form. They begin life as a small immobile creature from which asexually fragmented siblings can separate, each with their own distinct personality. A later stage resembles a parasitic lamprey, followed by a large clam inside which the head is visible. The next oldest form resembles a trilobite. Other stages included an urchin-like state, and later a flat fish-like appearance. A prominent Decapodian, Dr. Zoidberg, reverted through all of these early "larval" life cycle stages of his species after being exposed to a youth tar. ("Teenage Mutant Leela's Hurdles".) When Decapodians mate, they quickly die off, leaving their young to grow without parents to guide them. ("Why Must I Be a Crustacean in Love?".)