animalcule vs animalculum

animalcule and animalculum both are nouns.

Word	Noun	Adjective	Verb	Adverb
animalcule	Yes	No	No	No
animalculum	Yes	No	No	No

As nouns, animalcule and animalculum are synonyms defined as:

animalcule and animalculum: microscopic organism such as an amoeba or paramecium

animalcule (noun)	animalculum (noun)
microscopic organism such as an amoeba or paramecium	microscopic organism such as an amoeba or paramecium