It's not on my head, but we found a juvenile day octopus in Oahu on a scuba dive! It was swam back down to the floor where the fish wouldn't eat it.
@Thales
I also got super lucky and found a baby hiding in a muscle shell in the surf on Maui. It was about the size of a silver dollar (for those of you old enough to remember those). I couldn't figure out why there was a squishy thing in a dead shell, then it popped out into the ocean so I caught it to show a few people. Then was quite happy to be out back in it's hide and released back to the reef.
I also got super lucky and found a baby hiding in a muscle shell in the surf on Maui. It was about the size of a silver dollar (for those of you old enough to remember those). I couldn't figure out why there was a squishy thing in a dead shell, then it popped out into the ocean so I caught it to show a few people. Then was quite happy to be out back in it's hide and released back to the reef.