The Bacteriophage are nuts. They are the single deadliest creature on the planet, killing millions every day. Why hasn’t the world been wiped out yet? Simple: Phages are microscopic.
Phages only kill cells, which can reproduce much quicker than they can be eaten. Phages make up more of Earth’s lifeforms than every other creature combined, including bacteria. The way a Phage kills things is simple: a Phage finds a cell, jabs it with a sort of fleshy needle located between it’s 6 legs, then injects its genetic code. The cell is kind of brainwashed and is forced to create more Phages, and then those Phages release an enzyme that causes the cell to burst open. The Phages inside are then released, and the cycle continues. Phages are incredibly accurate hunters, seeking only a single cell and some close family. There are more than one kind of Phage, so all kinds of cells are hunted.
Phages also provide potential medical uses to deal with Superbugs (antibiotic resistant bacteria and viruses). As bacteria become more antibiotic resistant, they have to give up Phage resistance. So using Phages and antibiotics at the same time could kill any kind a bacteria, no matter how resilient. It seems like a wonderful idea, but medical companies are skeptical, since we don’t have any proper testing to prove it would work without side effects. This means it probably won’t be used on any scale bigger than trialing for a long time.