Common character in tapeworm and earthworm is
Bilateral symmetry is a common characteristic of tapeworm (Platyhelminthes) and earthworm (Annelida).
Metamerism and schizocoelom are observed in earthworms (not tapeworms).
Gut is absent in tapeworms. One-way gut (incomplete digestive system) is observed in other flatworms, roundworms, earthworms (Annelida), etc..