There may be more than one species of thin, bright red sponges that encrust the undersurfaces of rocks on lagoon, pinnacle and seaward reefs, but they would be difficult to tell apart from photos. Here are some samples.
The nudibranch Jorunna funebris is not known to eat red sponges, but it looks as though there could be a grazed spot in front of the larger one.
The Goniobranchus albopustulosus below appears to be just passing over this red sponge.
Created 1 June 2019