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.

[1] 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.

[2] The shell of Cassis tuberosa is typically cream colored with dark brown spots.

[3] The minimum recorded depth for this species is 0 m.[2] and maximum recorded depth is 27 m.[2] The species resides in shallow coastal waters around sandy beaches, as well as reef environments.

Due to their preference for shallow waters, they are easily accessed by tourists.