This curious little chap was floating along on the surface of the water
near a reef off the coast of Oahu's North shore.
The body was about 3/8" in diameter. The "legs" were normally extended,
as pictured, but would retract when touched. Each leg was bifurcated at
the end. The photo doesn't do the deep blue colour of the creature
justice:

img src="http://pcbunn.cacr.caltech.edu/jjb/aquarium/creature2.jpg"

It reminds me of a flying saucer. Is it some sort of nudibranch?