Given a scientific passage and an answer, generate a question for the given answer.

Passage: The single-celled prokaryotic organism otherwise known as bacteria. And all it takes is one to quickly grow, under just the right conditions, into millions and billions. Luckily, we know how to control bacteria when necessary. But bacteria do serve many important purposes. In fact, we could not survive without them. Answer: single-celled prokaryotic
What type of organism is a bacteria?