Football-shaped seabird with crisp patterning. Dark brownish-black above with white belly. Head entirely dark in breeding plumage; nonbreeding show white face with curved dark line below eye. Sides usually show some messy dark streaks. Bill is longer and more slender than similar Thick-billed Murre; but can be difficult to judge at a distance. Also note browner plumage and streaky sides on Common Murre. Breeds in colonies on rocky islands and cliffs; spends the rest of the year on the ocean. Usually single or in loose small groups; in the Atlantic, sometimes seen in loose association with Razorbills.