In biology, a lorica is a shell-like protective outer covering, often reinforced with sand grains and other particles that some protozoans and loricifera metazoans secrete. Usually it is tubular or conical in shape, with a loose case that is closed at one end.  An example is the protozoan genus Stentor, in which the lorica is trumpet-shaped. In the tintinnids, the lorica is frequently transparent and is used as domicile. Halofolliculina corallasia has a lorica that is attached as an outer structure, and into which it retracts when disturbed.
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- "Mic-UK: TINTINNINAE". www.microscopy-uk.org.uk. Retrieved 2009-08-16.
- "Protozoan plankton ecology – Three phases of lorica formation". books.google.com. Retrieved 2009-08-16.