The popular science conception of carcinization is that the crab body plan is so evolutionarily superior that, in time, all animals will evolve into crabs. However, this is an oversimplification and carcinization can be defined as the process of a decapod crustacean convergently evolving the characteristics of a crab. The most important of these characteristics include a depressed and shortened carapace with a similar width and length, a wide sternum, and a pleon ventrally folded within the carapace.  The purpose of this research is to examine carcinization as a phenomenon among decapod crustaceans and explain how it demonstrates convergent evolution. Full carcinization has occurred at least five times in crustacea: twice in the infraorder Brachyura, or the “true” crabs, and three times in the infraorder Anomura, the “false” crabs. These instances of carcinization have been verified through probe design, anchored hybrid enrichment sequencing and dataset assembly, phylogenomics, and divergence time estimation using fossils. The Brachyuran carcinization events include sections Dromiacea, which include sponge crabs, and Eubrachyura, the more derived and diverse of the two sections with 6,191 extant and 1,265 extinct species. The carcinization events in Anomura include the members of the family Porcellanidae, Lomisidae, and Lithodidae. Some Porcellanid crabs even demonstrate hypercarcinization, or the convergent evolution of Brachyuran-like characteristics beyond those typically associated with carcinization. This presentation synthesizes contemporary sources to support the evolutionary link between Litholid king crabs and a Pagurid hermit crab ancestor, a potential connection that has been long denied by prominent evolutionary biologists.