Common eiders (Somateria mollissima) are the largest duck found in the northern hemisphere. The male's bright white, black, and green plumage contrasts markedly with the female's camouflaging dull striped brown. The scientific name of the duck is derived from Ancient Greek somatos "body" and erion "wool", and Latin mollissimus "very soft", all referring to its down feathers. They are stocky, thick-necked birds that hold their heads below body level during flight. The eider's nest is built close to the sea and is lined with the celebrated eiderdown, plucked from the female's breast. Eider down, famous for its insulating qualities, is used in large amounts in the nest lining, helping to keep the eggs warm in frigid northern climates. Although eiderdown pillows or quilts are now a rarity, eiderdown harvesting continues and is sustainable, as it can be done after the ducklings leave the nest with no harm to the birds.