Roundworms are important.

  All roundworms are not a problem. Some are a beneficial to us, because they feed on fleas, termites, ants,beetles and many others that could damage crops. They are also are beneficial because they kill deer ticks, which causes Lyme disease. Also because they are key to health of the soil. They provide nutrients and break down organic material. Also they help with cycling nutrients such as nitrogen. So as you can tell roundworms are not always bad.
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