carcinization
The convergent evolution of decapod crustaceans from forms dissimilar to true crabs into similar forms.
uncountable
[L]arval forms of the two groups [hermit crabs and king crabs] are remarkably alike; and carcinization (the evolution of crablike features) appears to have been a recurring theme in hermit crab evolution under ecological circumstances where the shells of gastropod snails are of limited availability (as for example in the deep sea).
Where it comes from
From Ancient Greek καρκῐ́νος (karkĭ́nos, “crab”) + English -ization (suffix forming nouns denoting the act, process, or result of doing or making something), coined by British zoologist Lancelot Alexander Borradaile (1872–1945) in a 1916 report: see the quotation.
Adapted from the Wiktionary entry carcinization (CC BY-SA 4.0).