What is Clam?
[[Image:LittleNeck clams USDA96c1862.jpg|thumb|Littleneck clams; they are ''Mercenaria mercenaria''.]] A '''clam''' is a type of [[shellfish]]. Clams can be found in [[saltwater]] and [[freshwater]]. This is a common usage term, and so includes quite a variety of shellfish. Clams are a fairly common form of [[bivalve]], therefore making it part of the phylum [[Mollusc]]. There are many clams in the [[ocean]], but some can also be found in some lakes, streams, and rivers. The word 'clam' is often applied to those that are [[edible]] and live most of their lives halfway buried in the seafloor. Clams have two shells of equal size connected by two aductor muscles and have a powerful burrowing foot.<ref>{{cite encyclopedia |url=https://www.britannica.com/animal/clam |title=Clam |encyclopedia= Encyclopædia Britannica |publisher=Encyclopædia Britannica |date=2016}}</ref> Clams for [[cooking]] do not live attached to rocks (whereas [[oyster]]s and [[mussel]]s do). Clams are often got by digging and cooked and served as [[clam chowder]]. They may be found on menus in [[restaurants]] that serve [[seafood]]. Clams eat [[plankton]], and are eaten by small [[sharks]] and [[squid]]. Clams have a burrowing foot that they use to dig down into the sand or mud to hide. The shell has three layers. The top one is called mother-of-pearl because it is a coating of pearl material. A living freshwater clam can work like a filter in fish tanks to keep the water clean. == Life span == Some clams have life cycles of only one year, while at least one may be over 500 years old.<ref>{{cite web |url=http://www.cbsnews.com/8301-205_162-57612409/ming-the-clam-worlds-oldest-animal-was-actually-507-years-old/ |title=Ming the Clam, World's Oldest Animal, Was Actually 507 Years Old |publisher=CBS News |author=Danielle Elliot |date=14 November 2013 |accessdate=15 November 2013 |archive-date=20 November 2013 |archive-url=https://web.archive.org/web/20131120153638/http://www.cbsnews.com/8301-205_162-57612409/ming-the-clam-worlds-oldest-anima