Molluscs are indirectly harmful to man but most of them are beneficial. Molluscs are of great important in various ways. There are some benefits of molluscs:
1. The harmful molluscs ate slugs and shipworms. Slugs are injurious in gardens and cultivations. They not only eat leaves but also destroy plants by cutting up their roots and stems. Teredo, a shipworm damages wooden parts of ship.
2. Many mollusks are great source of food for man in many parts of world. Large quantity of calms, oysters and mussels are eaten in Fareast, Europe and America. Oysters are regarded as delicacy.
3. Shell of fresh water mussels is used in button industry.

4. The shell of oyster are mixed with tar for making roads in America.
5. Shells in certain parts of world are also used for making ornaments.
6. Some oysters also make valuable pearls e.g. the pearl oyster.
7. Some pearls are used for making jewellery.
8. Some animals including in this phyla are use to eat in some countries.