Posted: 24/09/2016 at 10:20
Lots of the lower forms of life look similar rachel.
Human thread worms have no other host and don't live outside the body as worms. Eggs leave the human body to me recirculated by those who don't watch their hands after contact with their sh.t.
I imagine it's much the same for other intestinal worm species, though some have a secondary host in the cycle. Worm inside host, eggs outside.