Author: Debbie (173.243.87.---)
Date: 03-23-12 13:44
Alright, Diving Debbie here!
It was most likely a remora in all scenarios described here. They are flat on the bottom and attach themselves to and/or cruise along with large animals, usually rays, turtles and sharks. They do this on top of the animal and underneath as well; they can cruise and ride upside down. If you see a remora while in the water, you know there is some large "host" nearby. They have symbiotic relationships with the host, as they are cleaners, and are feeding off of the parasites found on the host animals.
If they can't find a host, they often will attach to a diver or a boat as well.
Here in Culebra, they are silvery to grayish to black. According to Humann's Reef Fish ID book, they can be anywhere from 10-18 inches long, with a max up to 3.5 feet.