There are different types/species of flatworms. A flatworm is in the family of platyheliminthes and has a flat body with bilateral symmetry. They also have soft but solid body … 's. If I'm not mistaken, they are parasitic life forms. flatworm is in the family of platyheliminthes and has a flat body with bilateral symmetry. They also have soft but solid body … 's. If I'm not mistaken, they are parasitic life forms.