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Updated 4/19/2026

Family Cassidae

HAWAII - ENDEMIC

Semicassis umbilicata  



Haleiwa, Oahu, 120 feet
(Woody Woodman collection)


Oahu (Mel Pang collection)

Haleiwa, Oahu, 100 feet

 

GROOVED HELMET

Uncommon in sand deeper than 75 feet.  Attains 3.3 inches, 83 mm  Endemic to Hawaii. Formerly known as Phalium umbilicatum.