Mollymawks belong to the albatross family, Diomedeidae, which shares the order Procellariiformes with shearwaters, fulmars, storm petrels, and diving petrels. Procellariiformes have certain identifying features. They have nasal passages that attach to the upper bill, called naricorns (although the nostrils on the albatross are on the sides of the bill). The bills are also unique in that they are split into between seven and nine horny plates. They produce a stomach oil made up of wax esters and triglycerides that is stored in the proventriculus. This is used against predators as well as an energy-rich food source for chicks and for the adults during their long flights. They also have a salt gland that is situated above the nasal passage and helps desalinate their bodies, required due to the high amount of ocean water that they imbibe. It excretes a high saline solution from their nose.