 The seed is then typically reared in a nursery environment, where it is transferred to a material with a suitable surface for later relocation to the growing area.After about three months in the nursery, mussel seed is "socked" (placed in a tube-like mesh material) and hung on longlines or rafts for grow-out.Within a few days, the mussels migrate to the outside of the sock for better access food sources in the water column.