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''Volborthella'' is an animal of uncertain classification, whose fossils pre-date . It has been considered for a period a cephalopod. However discoveries of more detailed fossils showed that ''Volborthella''’s small, conical shell was not secreted but built from grains of the mineral
silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...
(silica), and that it was not divided into a series of compartments by
septa The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly 4 million people in five c ...
as those of fossil shelled cephalopods and the living ''
Nautilus The nautilus (, ) is a pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in ...
'' are. This illusion was a result of the laminated texture of the organisms' tests. Therefore, ''Volborthella''’s classification is now uncertain. It has been speculated that it may in fact represent a
sclerite A sclerite (Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly ...
of a larger organism, on the basis of one specimen; however, it may be premature to accept this hypothesis, as the arrangement of sclerites producing this impression may have occurred by chance. The Ordovician scleritome-bearing '' Curviconophorus'', as well as the Halwaxiids, lobopods and echinoderms, demonstrate the diversity of organisms which may produce a scleritome of this nature. The related ''Campitius'' was originally suggested to be part of a
radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...
rather than a scleritome, but is now considered a synonym of ''Volborthella''. ''Volborthella'' is widespread, and a useful biostratigraphic indicator; it has been found in
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
,
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...
,
Spitsbergen Spitsbergen (; formerly known as West Spitsbergen; Norwegian: ''Vest Spitsbergen'' or ''Vestspitsbergen'' , also sometimes spelled Spitzbergen) is the largest and the only permanently populated island of the Svalbard archipelago in northern Nor ...
, and
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, and is restricted to
Lower Cambrian The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago ( ...
rocks, appearing before the trilobites and co-existing with them for some time. ''Volborthella'' has been described as a 'failed attempt in mineralisation'; it constructed its wall by agglutinating grains of sediment, much like some foramanifera, and declined in conjunction with the origin of truly-
biomineralising Biomineralization, also written biomineralisation, is the process by which living organisms produce minerals, often to harden or stiffen existing tissues. Such tissues are called mineralized tissues. It is an extremely widespread phenomenon; ...
organisms. However, its similarity to ''
Salterella ''Salterella'' is an enigmatic Cambrian genus with a small, conical, calcareous shell that appears to be septate, but is rather filled with stratified laminar deposits. The shell contains grains of sediment, which are obtained selectively (with a ...
'', which contained embedded sediment grains in its mineralised wall, suggests a possible biological relationship - ''Salterella'' may have begun to mineralise its agglutinated wall. Some ''Volborthella'' specimens do show
taphonomic Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term ''taphonomy'' (from Greek , 'burial' and , 'law') was introduced to paleontology in 1940 by Soviet scientist Ivan Efremov t ...
hints that some form of lightly mineralised sheath may have enclosed its agglutinated shell.


References

{{Taxonbar, from1=Q18519633, from2=Q5150695 Enigmatic prehistoric animal genera Controversial taxa