Octopus are said to be perhaps the most intelligent non-mammals in the sea. They, and their cousins the squid and cuttlefish, are always intriguing underwater, seeming to be simultaneously scrutinizing you and trying to camouflage themselves so you won't notice them. I find them fascinating!
"Walking" cuttlefish (4-5 inches long) - this was behavior I've never seen before. The cuttlefish used two of its tentacles as if they were feet, and walked a considerable ways along the sand. I have no idea why!
Flambouyant cuttlefish (4-5 inches long) trying to make her body look as prickly and dangerous as possible so I won't bother/eat her.