During last nights dive I was watching some little crabs on a coral when I saw what at first appeared to be some detritus just inching its way down the coral. It appears to be segmented and fairly flexible and very very small. If the images posted here are not visible I can send the original images if necessary.
Caprellid amphipod aka skeleton shrimp
It's an amphipod in the family Caprellidae. These are commonly called skeleton or ghost shrimp even though they're not shrimp at all. Some are predators while others are micro-grazers on micro algae & organic film. The one you photographed has enormous antennae compared to its size.
( Hi Jim. )
I spend hours in the ocean just looking and looking for something to stump all the brainiacs here on Wetpixel and my What-is-it questions are answered before I can refresh my screen... :-P
(Hi Leslie, the fellow I am talking to is vacationing, err, working at DEMA and wont be back for a day or so.)