These may be Aseraggodes melanostictus, but the ID is tentative. We have seen these at night in channels along the seaward reef at depths of about 15 to 20m, usually on sand. Ours were estimated at 30 to 50mm long.
In this close up, the tubular nostril characteristic of this genus is just to the left of the eyes.
Created 3 August 2017