Spirillinida

The Spirillinida were separated from the Rotaliida 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