Parascaris equorum is a species of ascarid that is the equine roundworm. Steller also identified an endoparasite in the sea cows, which was likely an ascarid nematode. "Ascaris lumbricoides" and in ascarid parasitoses in general (including threadworm parasitosis). All these ascarid eggs are similar in appearance to "Heterakis gallinarum". "Ascaris lumbricoides" is the main ascarid parasite of humans, causing Ascariasis.