Whenever a player taps on a screen, there is 1% chance to spawn a critical bacteria that will give him 5 times more bacteria than his current BPC.
Critical bacteria have red spots and additional tentacles.
Critical Hit modifiers
Some evolved bacteria have stats that increase critical hit chance and critical hit effect.
After researching Quantum Robotics in the Dark Matter Institute, each tap also has a 0.1% chance to produce a nanobot, but it is not affected by increased critical hit chance and effect.