{{Short description|Species of gastropod}} {{Citation style|date=May 2026}} {{Speciesbox | image = Cassis tuberosa.png | image_caption = A live ''C. tuberosa in situ'' | status = G4 | status_system = TNC | status_ref = <ref name=NS>{{cite NatureServe |id=2.902553 |title=''Cassis tuberosa'' |access-date=7 April 2026}}</ref> | taxon = Cassis tuberosa | authority = (Linnaeus, 1758) | synonyms = {{Species list |Buccinum tuberosum|Linnaeus, 1758 |Buccinum striatum|Gmelin, 1791 |Cassis (Cassis) tuberosa|(Linnaeus, 1758) |Cassis triangularis|Coulon, 1936 |Cassis triquetra|Rigacci, 1866}} | synonyms_ref = <ref name=WoRMS>{{cite WoRMS |title=''Cassis tuberosa'' (Linnaeus, 1758) |id=224977 |db=mollusc |access-date=19 May 2026}}</ref> }}

'''''Cassis tuberosa''''', the '''king helmet''', is a species of very large sea snail with a solid, heavy shell, a marine gastropod mollusc in the family Cassidae, the helmet shells and their allies.<ref name=WoRMS/>

== Distribution == This species occurs in the Western Atlantic Ocean in: North Carolina, Florida, Mexico, Honduras, Colombia, Costa Rica, Panama, Venezuela, Bermuda, Bahamas, Turks & Caicos, Cuba, Hispaniola, Puerto Rico, Virgin Islands, Leeward Islands, Windward Islands, Brazil, and in the Eastern Atlantic Ocean at the Cape Verde Islands. [http://www.malacolog.org/search.php?nameid=2804]{{dead link|date=May 2026}}

thumb|Ventral side, animal alive but soft parts retracted

== Description == The maximum recorded shell length is 301&nbsp;mm.<ref name="Welch 2010">Welch J. J. (2010). "The "Island Rule" and Deep-Sea Gastropods: Re-Examining the Evidence". ''PLoS ONE'' '''5'''(1): e8776. {{doi|10.1371/journal.pone.0008776|doi-access=free}}.</ref> The shell of ''Cassis tuberosa'' is typically cream colored with dark brown spots. The dorsal surface will have fine growth lines and fine spiral lines to create a "canceled effect".<ref name="Dias et al. 2017">Dias et al. (2017). "What do we know about Cassis tuberosa (Mollusca: Cassidae) a heavily exploited marine gastropod?". [https://www.researchgate.net/profile/Rafaela_Duarte2/publication/319323363_What_do_we_know_about_Cassis_tuberosa_Mollusca_Cassidae_a_heavily_exploited_marine_gastropod/links/5e7359f9a6fdcc37caf653b0/What-do-we-know-about-Cassis-tuberosa-Mollusca-Cassidae-a-heavily-exploited-marine-gastropod.pdf]</ref>

== Habitat == The minimum recorded depth for this species is 0 m.<ref name="Welch 2010"/> and maximum recorded depth is 27 m.<ref name="Welch 2010"/> The species resides in shallow coastal waters around sandy beaches, as well as reef environments. It lives in tandem with seagrass beds, macroalgae banks, rhodolith beds and coral rubble.<ref name= "Dias et al. 2017" />

== Human use == The shell of this species has been used for creating cameos.{{citation needed|date=May 2026}}

The attractiveness of the shell is one of the main reasons ''C. tuberosa'' is taken for human use. Due to their preference for shallow waters, they are easily accessed by tourists.<ref name= "Mota et al. 2020">Mota, E. L. S., Alves, R. R. da N. and Dias, T. L. P. (2020) “Fishing, trade, and local ecological knowledge of the marine gastropod, Cassis tuberosa – a target species of the international shell trade”, ''Ethnobiology and Conservation'', 9. Available at: [https://www.ethnobioconservation.com/index.php/ebc/article/view/315]</ref>

==References== {{reflist}}

== External links == * [http://www.malacolog.org/search.php?nameid=2804 Malacolog]{{dead link|date=May 2026}}

{{Taxonbar|from=Q2941308}}

Category:Cassidae Category:Gastropods described in 1758 Category:Animal taxa named by Carl Linnaeus Category:Molluscs of the Atlantic Ocean