The stick can be planted on a Mussel Bed. Later the Mussels can be harvested, consuming the stick, the Mussel Bed, and giving 1, 3, or 6 Mussels (depending on how long ago the stick has been planted). The number of Mussels is indicated by how much of the stick is covered in them. New Mussel Beds will spawn randomly to replace those consumed, additionally they can also be crafted and planted by the player.
Mussels attached to the Mussel Stick do not spoil, making it an excellent tool for creating an emergency food supply. Given enough time has passed after planting, each planted stick will yield 6 mussels.