Mepụta ụdị nke ahịrịokwu a dị mgbagwoju anya Ihe akara pallial bụ akara (akara) dị n'ime nke ọ bụla na mkpuchi nke mkpuchi nke mollusk bivalve.
N'ezie, ụdị okwu dị mgbagwoju anya nke ahịrịokwu ahụ bụ "Okporo pallial bụ akara dị n'ime ime nke valvụ nke shell nke mollusk bivalve ebe akwara mantle na-ejikọta, nke na clams nwere akwara abụọ na-ejikọkarị akara ebe akwara adductor na-ejikọta. "