Everyone stops to take a picture. I’ve seen him or his kin many a time. No big deal. So, a new day, a new angle, try something, work the scene. Ah! Close-up. It looks like a flap over his pupil.
Hmmm, now I got questions. Meanwhile how do fish wash themselves? It’s not like they have arms or soap to use. This guy looks like he could use some derm-abrasion. Oh, the opening behind the eye is the gill opening. At least that’s my story on that.