Bacteria Mod is a partially found Minecraft mod created by TeNNoX for versions 1.7.10 and 1.8. It had a block called the bacterium colony, which can be used to summon a colony of bacteria to eat away certain blocks.
As of May, 31st 2022, only one confirmed link has been found but only of the 1.8 version:
https://mc-pc.net/mods/227-bacteria.html
A bunch of videos remain online of the mod's existence, most notably by DanTDM and PopularMMOs.
A site created by TeNNoX hosts all known versions of the Bacteria Mod from 1.5 to 1.8, as well as his other mods.