This strange looking fellow is a sea Hare, their name comes from them resembling a rabbit but I see little that reminds me of a rabbit or hare. They are from the same family as Nudibranch or sea slugs, it's basically a shell-less snail. Quite large this one about the size of a adult hand, they can be found all over the planet in many varieties. As a defense mechanism they can squirt ink out to confuse prey somewhat in the way a Octopus would, this doesn't deter turtles who enjoy snacking on them.