page_title: Mollusc shell
hierarchical_section_title: Mollusc shell
caption_attribution_description: Deutsch: Amerikanische Bohrmuschel, gefunden am Strand von Juist im Mai 2008
context_page_description: The mollusc shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, which includes snails, clams, tusk shells, and several other classes. Not all shelled molluscs live in the sea; many live on the land and in freshwater.
  The ancestral mollusc is thought to have had a shell, but this has subsequently been lost or reduced on some families, such as the squid, octopus, and some smaller groups such as the caudofoveata and solenogastres. Today, over 100,000 living species bear a shell; there is some dispute as to whether these shell-bearing molluscs form a monophyletic group or whether shell-less molluscs are interleaved into their family tree.
  Malacology, the scientific study of molluscs as living organisms, has a branch devoted to the study of shells, and this is called conchology—although these terms used to be, and to a minor extent still are, used interchangeably, even by scientists.
  Within some species of molluscs, there is often a wide degree of variation in the exact shape, pattern, ornamentation, and color of the shell.
context_section_description: The mollusc (or mollusk) shell  is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, which includes snails, clams, tusk shells, and several other classes. Not all shelled molluscs live in the sea; many live on the land and in freshwater.
  The ancestral mollusc is thought to have had a shell, but this has subsequently been lost or reduced on some families, such as the squid, octopus, and some smaller groups such as the caudofoveata and solenogastres. Today, over 100,000 living species bear a shell; there is some dispute as to whether these shell-bearing molluscs form a monophyletic group (conchifera) or whether shell-less molluscs are interleaved into their family tree.
  Malacology, the scientific study of molluscs as living organisms, has a branch devoted to the study of shells, and this is called conchology—although these terms used to be, and to a minor extent still are, used interchangeably, even by scientists (this is more common in Europe).
  Within some species of molluscs, there is often a wide degree of variation in the exact shape, pattern, ornamentation, and color of the shell.
caption: Closed and open shells of a marine bivalve, Petricola pholadiformis. A bivalve shell is composed of two hinged valves which are joined by a ligament.
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