mussel shrimp vs ostracod

mussel shrimp and ostracod both are nouns.

Word	Noun	Adjective	Verb	Adverb
mussel shrimp	Yes	No	No	No
ostracod	Yes	No	No	No

As nouns, mussel shrimp and ostracod are synonyms defined as:

mussel shrimp and ostracod: tiny marine and freshwater crustaceans with a shrimp-like body enclosed in a bivalve shell

Other synonyms of mussel shrimp include seed shrimp.

mussel shrimp (noun)	ostracod (noun)
tiny marine and freshwater crustaceans with a shrimp-like body enclosed in a bivalve shell	tiny marine and freshwater crustaceans with a shrimp-like body enclosed in a bivalve shell