About 20 years ago, I was investigating amoeba and the Legionella bacteria living within them, in a collection from Timothy Rowbotham. We identified five new species of Legionella and also made a surprising discovery – Gram-positive chlamydia-like bacteria living in amoeba. We tried and tried to amplify the newly discovered microbe, but all our attempts came to nothing, until eventually we started to question if it was a bacterium at all. We inspected the amoeba under an electronic microscope before and after extraction, and saw something that wasn’t bacteria-like at all, but instead looked very much like a virus. What we originally thought was a Legionella-like bacteria turned out to be mimivirus, a giant 0.4–0.8 µm virus with a 1.2 megabase genome.