Apparently scientists are baffled as to what this thing is. I have a couple of suggestions: 1) Ocean ghost. 2) The lost Kardashian sister. 3) Wet alien invasion vanguard. 4) John Travolta's massage towel. 5) That thing you dream about only to wake up in a cold sweat and then all day you tell yourself that it's nothing and it would die if it left the ocean and then you feel better until next time you're at the beach and then you realize that you will never be able to go for a swim again and swimming was your favourite thing to do and now you don't even have that to brighten up your otherwise meaningless life.