A taxonomic course within the subphylum Crustacea — the ostracods.
An order of Entomostraca having shrimplike figures enclosed in tough bivalve shells; called also seed shrimp and mussel shrimp. These people were formerly known as Ostracoidea. They truly are of small size, and swim freely about; many are lower than 1 mm in total. Microfossils of specific extinct sales are discovered extending to the Cambrian age.