testacean vs rhizopod

testacean and rhizopod both are nouns.

Word	Noun	Adjective	Verb	Adverb
testacean	Yes	No	No	No
rhizopod	Yes	No	No	No

As nouns, rhizopod is a hypernym of testacean; that is, rhizopod is a word with a broader meaning than testacean:

testacean: any of various rhizopods of the order Testacea characterized by having a shell
rhizopod: protozoa characterized by a pseudopod

Other hypernyms of testacean include rhizopodan.

testacean (noun)	rhizopod (noun)
any of various rhizopods of the order Testacea characterized by having a shell	protozoa characterized by a pseudopod