HELPFUL TIP: To remove the beard from the mussels, grab it with your thumb and forefinger and tug it toward the hinge of the mussel shell. You can also use a knife to gently scrape away the beard.Ideally, you want to prepare and cook the mussels as soon after buying as possible, but as long as they’re fresh they will keep them overnight and for up to a day. Store them in a dry bowl or container covered with a damp tea towel.As for the mussels and their nutritional benefits, they’re impressive! Mussels are one of the best sources of protein and contain all the amino acids. They’re also very rich in iron.