The razor shell, Ensis arcuatus, also called razor clam or razor fish, is a bivalve

Bivalvia

Bivalvia is a taxonomic class of marine and freshwater molluscs. This class includes clams, oysters, mussels, scallops, and many other families of molluscs that have two hinged shells...

 of the family Pharidae

Pharidae

Pharidae is a family of clams related to the razor shells , a family which includes Pharidae by some authorities.-Genera:* Afrophaxas Cosel, 1993* Cultellus Schumacher, 1817* Ensiculus H...

. It is found on sandy beaches in Northern Europe

Northern Europe

Northern Europe is the northern part or region of Europe. Northern Europe typically refers to the seven countries in the northern part of the European subcontinent which includes Denmark, Estonia, Latvia, Lithuania, Norway, Finland and Sweden...

 and Eastern Canada

Eastern Canada

Eastern Canada is generally considered to be the region of Canada east of Manitoba, consisting of the following provinces:* New Brunswick* Newfoundland and Labrador* Nova Scotia* Ontario* Prince Edward Island* Quebec...

, such as Prince Edward Island

Prince Edward Island

Prince Edward Island is a Canadian province consisting of an island of the same name, as well as other islands. The maritime province is the smallest in the nation in both land area and population...

, where it is most populous in the world. It prefers coarser sand than its relatives E. ensis

Ensis ensis

Ensis ensis, or the sword razor, is a marine bivalve mollusc in the family Pharidae. It lives buried in the sand and is found off the coasts of north west Europe....

and E. siliqua.
It is known for its elongated, rectangular shape, whose similarity to the straight razor

Straight razor

A straight razor is a razor with a blade that can fold into its handle. They are also called open razors and cut-throat razors.Although straight razors were once the principal method of manual shaving, they have been largely overshadowed by the safety razor, incorporating a disposable blade...

 gives it its name. The razor shell has been known to reach 23 centimetres (9.1 in) in length.