Yup, it's a sea cucumber...the "head" part.
I hadn't seen one with this colouring nor this pattern before. He was huge...about 2' long. Deep, too...29m. All by himself, tooling along nice and slow.
Thanks for letting me know, Gilligan...I am totally paranoid about what I post now as it all looked good on my screen before!! I really appreciate you taking the time to reassure me (or to let me know that something is wrong!)
lisa...I can zoom in and get more detail, but nothing really exciting pops out. For me, I need this much of the animal in the shot to get that surreal feeling but still know what it is! I probably should have a play with different crops/zooms...