This thin, dark blue encrusting sponge lives under rocks in shallow water, generally a couple of meters or less. This colony has been grazed by the dark blue nudibranch Doris pecten. The sponge has also been identifed on iNaturalist as Terpios granulosus. I'm not sure how to tell the difference, but Young (1967) reported Doris pecten at Enewetak Atoll, Marshall Islands, eating the blue sponge T. aploos, and Sea Slugs of Hawaii says the same for Hawaiian specimens, so we will leave this as T. aploos, a species described from the west central Pacific.
Created 2 June 2019