Jeff---I've been known to be crazy before---just ask some on this forum---but it certainly looks man made to me. The dark spot isnt consistant with anything else there. With the numbers at the top left of the screen, you have the 'fork target' with the 'black squiggley'. To the left you have what looks like a coral boulder sitting on 'something'. Tha t 'something' has a coral color to it, but maybe just sand and coral dust from the ROV. Now I dont want to make conjecture here, but it looks like an inviting target.
Tom