The name comes from the Greek priōn, meaning "saw", a reference of the serrated edges of the birds' saw-like bill.

[3] Prions grow 20 to 27 cm (7.9–10.6 in) long, and have blue-grey upper parts and white underparts.

Three species of prion have flattened bills with a fringe of lamellae that act as strainers for zooplankton.

[4] All prions are marine and feed on small crustacea such as copepods, ostracods, decapods, and krill, as well as some fish such as myctophids and nototheniids.

The oldest comes from the Late Miocene (Tortonian, some 7 to 12 million years ago) of the Bahía Inglesa Formation in Chile.