A roundworm has no segmentation.
A roundworm has no heart or formal blood vessels.
A roundworm reproduces sexually. The female has an ovary, holds eggs in an oviduct and then passes them to the uterus, where they are fertilized. The male has sperm cells are made in the testis and stored in the vas deferens. When it is time to reproduce, the sperm cells pass through the spicule. Eggs can be deposited in the soil once fertilized.