These all appear to be the same species of Elysia. The small animals were found in shallow water around Kwajalein. These look somewhat like our photos of Elysia sp. e296 and may just be better photos of that small species.
The 8mm specimen in the three photos below was found by Christina Sylvester in about 2m of water off Kwajalein's north point lagoon. She has also observed specimens in Kwajalein reef quarries.
Created 12 December 2015
Updated 19 March 2017