What are nematodes primarily known as?

Nematodes are primarily known as microscopic roundworms, which is why the correct answer is that they belong to this classification. They are a diverse group of organisms that can be found in a variety of environments, including soil and water. Their microscopic size means they often go unnoticed, yet they play significant roles in ecosystems, such as nutrient cycling and soil health.

In the context of plant health and agriculture, some nematodes can be beneficial, while others can be pests that negatively impact crop production. This dual nature is essential to understand, as it shapes how they are managed in agricultural and horticultural practices. Recognizing nematodes specifically as microscopic roundworms emphasizes their biological classification, which is crucial for understanding their behavior and impact in different environments.