Answer:
Animalcules
Step-by-step explanation:
Antonie van Leeuwenhoek, the Dutch scientist who is considered to be the father of microbiology, referred to bacteria as "animalcules" or "little animals". This was because he observed them under his simple microscopes and thought they were tiny animals, rather than single-celled microorganisms. It wasn't until later that the term "bacteria" was coined to refer specifically to these types of microorganisms.