Paradox, I'm sure it's the same type as mine. It's not skin peeling off I think, but actually some very compact skinlike secretion. Perhaps this protects it from injury by abrasion when it buries in the sand? Mine was only about 3 or 4 inches mantle length.
Mine never adapted well to captivity - it was VERY prone to inking, and it's secretions seemed to greatly irritate the Sepia pharoanis. it got stuck between some rockwork and secreted a different kind of mucous to free itself, HUGE amounts of slime in seconds. I had to remove it from the tank and change most of the water to clear out the secretions. While I was doing this I had to take the S. pharoanis out too. I thought it had calmed down a bit and stopped secreting, and had the two cuttles (the slimer separated in a plastic basket) in the same container as I did the water changes. Big mistake. I checked back and there was a slimy white foam covering the surface (had an airstone in there). The slimy one was fine, unaffected by it's slime, but the Pharoah was catatonic. I rushed the pharoah back to it's tank in a plastic bag and had to introduce it to clean water more quickly than normal, so I let a little water into the bag. It's tentacles were hanging loose (very bad sign indeed). In a few minutes I released it, but it's tentacle suckers stuck to the bag as it tried to come out. It couldn't let go. I gently eased the suckers off, afraid it was going to tug its tentacle off trying to jet out. That's when it jetted out and hit the side of the tank, leading to butt burn that has since got infected. He slowly recovered over the next 24 hours, but has never really been the same since then. He has also been fighting the infection ever since (more than a month ago).
As for the S. aculeatus (I think) I could not reintroduce it to the tank and had to keep it separately. Unfortunately this species is very prone to JUMPING OUT, and this is what it did! It did not last long after that.
I thought I was bringing home another Pharoah when I bought it. Having said all this, the two did not fight and their attempts at communication seemed to indicate that they did not "speak the same language", and so basically ignored one another. If not for the horrible secretions they might have co-existed well, as they are active at different times and not agressive to one another.
I would like to try S. aculeatus again but with its own species and a proper lid to prevent jumping. I suspect they are pretty tolerant about water quality considering that they are not much affected by their own noxious slime. They seem to need a few inches of soft sand, lots of cover, and are more active at night. Rockwork against the glass is a bad idea as they can get stuck. They are extremely interesting
I will try and post my video as well.