| Clue | Source | Date |
|---|---|---|
| Round bacterium | Commuter | 15 Jan 2024 |
| Bacterium which is spherical or nearly so | The Times Specialist Sunday | 22 Nov 2020 |
| Spherical bacterium | ||
| Spherical bacterium | New York Times | 24 Nov 2019 |
| Spherical bacterium | Wall Street Journal | 04 Jun 2016 |
| Oval bacterium |