A ribbon worm falls under the phylum Nemertea.

Bilateral.

The ribbon worm is an example of a species in the phylum Nemertea. These worms are known for their long, ribbon-like bodies and are found in marine environments worldwide.

Tubulanus polymorphus, Tubulanus albocinctus, cerebreus lacteus, these are just a few.

Carl-Erik Cantell has written:

'Studies on the morphology, taxonomy, and larval development of heteronemertines (Nemertina)' -- subject(s): Nemertea

'Some developmental stages of the peculiar Nemertean larva pilidium recurvatum Fewkes from the Gullmarfjord (Sweden)' -- subject(s): Larvae, Nemertea, Platyhelminthes