Nema refers to a genus of roundworms, commonly known as nematodes. These microscopic organisms are found in various environments, including soil, freshwater, and marine ecosystems. Nematodes play essential roles in nutrient cycling and soil health, as they help decompose organic matter and control pest populations. Some nematodes are beneficial, while others can be harmful to plants and animals. For example, plant-parasitic nematodes can damage crops, leading to significant agricultural losses. In contrast, free-living nematodes contribute positively to soil fertility and ecosystem balance. Understanding nematodes is crucial for both agriculture and environmental science.