A stylet is a hard, sharp, anatomical structure found in some invertebrates.
For example, the word stylet or stomatostyle is used for the primitive piercing mouthparts of some nematodes[1] and some nemerteans. In these groups the stylet is a hardened protrusible opening to the stomach. These stylets are adapted for the piercing of cell walls and usually function by providing the operative organism with access to the nutrients contained within the prey cell.
In octopodes, the stylets are internal, needle-like bent rods within the mantle, the vestigial remnants of an external shell.[4]
^"Digestive System". Nemaplex- The Nematode-Plant Expert Information System. Department of Nematology, University of California, Davis. Retrieved 26 November 2013.
^W. Allen Miller; Steven A. Whitham (2013), "Plant viruses", in David M. Knipe; Peter Howley (eds.), Fields Virology (6th ed.), Wolters Kluwer, p. 2311, ISBN9781451105636
^Lourenço, Sílvia; Moreno, Ana; Narciso, Luís; Pereira, João; Rosa, Rui; González, Ángel F. (September 2015). "Stylet (vestigial shell) size in Octopus vulgaris (Cephalopoda) hatchlings used to determine stylet nucleus in adults". Journal of the Marine Biological Association of the United Kingdom. 95 (6): 1237–1243. Bibcode:2015JMBUK..95.1237L. doi:10.1017/S0025315415000478. hdl:10261/124380.