For the first time, scientists have sequenced the genome of a mysterious species of giant bacterium that can be seen without a microscope.
Epulopiscium bacteria live symbiotically in the guts of a fish, Naso tonganus, in tropical ocean environments.
Most bacteria are too small to be seen without a microscope.
These single-celled mammoths have a million times the volume of their well-known relatives, E. coli, meaning they can just be made out with the naked eye.