Hiroyuki Kasuga of Southern Islander Dive Tours uploaded this video clip where a diver saw a strange face in the sand.
That turned out to be a species of stonefish (Synanceia), which often buries itself in the sand on the seabed, leaving just its eyes and mouth visible. The stonefish's mottled colorations complete the camouflage - it's very difficult to spot a hidden stonefish!
Stonefish are the most venomous fish known to man. Its venom contains potent neurotoxins secreted from glands at the base of their dorsal fins. Their penchant for burying themselves in the sand often results in swimmers accidentally stepping on them, and getting stung. Stonefish stings are extremely painful and, if left untreated, can be fatal.