I have this one identified as Doriopsis granulosa, although I notice Gosliner et al (2008) now consider it to be in the genus Doris. This species' gills are arranged in a more or less straight line across the back, like those of its relative, the smaller blue Doriopsis pecten. We have found at least 10 specimens, all at Kwajalein, ranging in length up to about 20mm. They live along lagoon reefs under rocks at depths of 5 to 10m.
Often when you find this species, it has sand grains adhering to its back.
On a shallow lagoon reef at Kwajalein on 22 February 2009, the egg mass below was observed under a rock. The Doriopsis granulosa was on the same rock, about 15cm away. It was coaxed over to the egg mass for the photos below. While we cannot be certain this nudibranch was responsible for those eggs--after all, the mass seems rather large for that small nudibranch--it was the only nudibranch we could find in the vicinity and the color matches quite well.
Created 15 December 2006
Updated 22 February 2009