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The word bacterium (the singular form of bacteria) comes from a Greek word that means “rod.” That's because the first bacteria discovered by scientists were shaped like rods as these types of bacteria are usually bigger and easier to see under a microscope. With the development of better microscopes, we know now that bacteria come in three basic shapes:
- coccus: spherical (like a marble)
- bacillus: rod-shaped (like a capsule pill)
- spirillus: spiral shaped (like a corkscrew)
