Asked by: FOCUS
Yes. Most bacteria are too small to be seen without a microscope, but in 1999 scientists working off the coast of Namibia discovered a bacterium called Thiomargarita namibiensis (sulfur pearl of Namibia) whose individual cells can grow up to 0.75mm wide. Its comparatively huge size is due to a hydrogen sulfide-filled gaseous cavity, which causes it to blow up like a balloon.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.