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Updated 10/16/2025

Family Cassidae

HAWAII - ENDEMIC

Semicassis umbilicata  



Oahu. @ Mel Pang

Haleiwa, Oahu, 100 feet

 

GROOVED HELMET

Uncommon in sand deeper than 75 feet.  Attains 3 inches.  Endemic to Hawaii. Formerly known as Phalium umbilicatum.