This small species is also tentatively identified. It is common at Kwajalein, found under rocks during the day and parasitizing sleeping fish at night. Often clusters of them are found on parrotfish and other fish sleeping on the reef after dark. More information on this parasitic relationship can be found at this link, where it is identified as Kogomea ovata.
The photos below show clusters of the shells on several different sleeping parrotfish.
Close and distant shots of a cluster of Hydroginella on a sleeping Scarus frenatus.
The photo below by Stan Jazwinski shows a couple of Hydroginella on a sleeping Calotomus carolinus at night.
The shells also parasitize sleeping wrasses, such as this Cheilinus trilobatus. Photo by Stan Jazwinski.
Created 13 October 2015
Updated 3 October 2022