The Spirillinida are an order of

foraminifera Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly ...

in which the

test Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film), ...

, or shell, primitively consists of an enrolled open tube, coming after the proloculus, wound planospirally or conically, commonly composed of an optically single crystal of

calcite Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scra ...

. The aperture is a simple opening at the end of the tube. Advanced forms with more than one chamber may consist of a few crystals, or rarely, a mosaic of crystals of calcite. The Spirillinida were separated from the

Rotaliida The Rotaliida are an order of Foraminifera, characterized by multilocular tests (shells) composed of bilamellar perforate hyaline lamellar calcite that may be optically radial or granular. In form, rotaliid tests are typically enrolled, but may ...

where they had been included as the Spirillinacea. However, not only is the spirillinid test rather distinct from typical rotaliid tests commonly composed of radially laminated calcite, but so are the protists distinct. The gametes produced by spirillinids during sexual reproduction are amoeboid in contrast to the biflagellate gametes produced by most other Foraminifera included rotaliids. Two living families are recognised. No superfamily has been established. The families are * Spirillinidae: The test consists of the single, coiled, tubular chamber, after the proluculus, composed of an optically single crystal of calcite. Example '' Spirillina'' * Patellinidae: The test is conical, multichambered, initial chamber after poroluclus tubular, two chambers in each later whorl. Example '' Patellina''

References

* * * {{Taxonbar, from=Q2311052 Tubothalamea Foraminifera orders