A style, sometimes referred to as a crystalline style (though there are no other biological kinds), is a rod made of

glycoprotein Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as g ...

located in the midgut of most

bivalves Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biv ...

and some

gastropods The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. ...

which aids in extracellular digestion. It consists of a protein matrix coated with digestive enzymes secreted by the style sac in the animal's stomach. When feeding, its projecting end is scraped against the stomach wall and abraded, thus releasing the enzymes. When subjected to starvation or desiccation, some bivalves have been known to re-ingest this organ.

References

Gastropod anatomy Bivalve anatomy Glycoproteins {{mollusc-stub