I spotted this in the sand at about 40-50 feet in Cozumel. It is about 3/4 of an inch long. It was being carried by the current on the bottom and generally liked to be curled up but did extend itself occasionally. What I find interesting is what appear to be vertebrae. Is this just a worm or a larval or intial phase fish of some sort. I think I see a rudimentary eye but could just be a dark mark. Does anyone know what it is?