Mussels are a filter-feeding lamellibranch mollusk with a high nutritional value, thanks to their high protein content. They are also a good source of iron. They are bivalve creatures, with symmetrical blueish-black shells that measure between 4 and 8 cm (1.5-3 inches). It naturally attaches itself to rocks using a filament it produces called a byssal thread, forming large colonies.
The estuaries of Galicia (Rías Gallegas) are an ideal habitat given the temperature and nutrients available in the seawater. The mussels grown here are of optimal size and quality. They are farmed on ropes hanging from large floating rafts, and they reproduce by laying millions of eggs. They reach a marketable size starting at one year of age. At this point, the ropes are pulled out of the water and they are cleaned on deck with lots of water and selected based on their size.