Well, OK, I think most of us know what this is... looks like a cuttlefish! (edit: it is, in fact, Sepioteuthis sepiodiea, the Caribbean Reef Squid; see Colin's reply to this thread.) TONMO.com visitor Nick B. let me share this photo with you to get your thoughts... What a remarkable pose!
According to Nick:

Thanks Nick for sharing!

Click to enlarge:I am the manager of our local dive clubs photo contest - and one of my friends took the photo below - at night, the creature was about 4 inches, taken in Florida Keys

Thanks Nick for sharing!