The cockroach of the microscopic world. A worm that is everywhere. Nematodes are unsegmented, cylindrical worms so numerous that if every other animal on Earth vanished, the outline of the planet would still be faintly visible, made entirely of nematodes. They live in the mud, the ice, the deep sea vents, and occasionally inside garden plants or pets. A worm that is indestructible. Free-living nematodes are the silent engines of the soil, breaking down bacteria and organic matter, releasing nutrients for plants to use. They are the unseen fertilisers, working tirelessly in the dark. However, some species are less benevolent, acting as parasites that stunt plant growth or cause illness in animals. They are masters of adaptation, capable of entering a state of suspended animation called cryptobiosis to survive extreme drought, heat or cold, waking up years later as if nothing happened. The life cycle is rapid. Depending on the species, a single female can produce hundreds of eggs, which hatch into tiny larvae that mature within days. Some species are predators, feeding on other microscopic animals. Others are decomposers, recycling nutrients from dead organic matter. To the naked eye, they are invisible threads, barely perceptible even under a microscope. Yet, their impact is colossal. They are the ultimate survivors, having outlived dinosaurs and ice ages. The soil is dark. The nematodes wriggle, invisible, breaking down bacteria, recycling nutrients. They do not know they are everywhere. They do not know they are indestructible. They just want to eat. To ignore the nematode is to ignore the very engine room of life itself. Nematodes were unknown to pre-European Māori due to their microscopic size. The concept of invisible spirits affecting health was well understood. The nematode is proof.